You can manually configure RTXI with many options. For example, you can run RTXI 2.0 using the RTAI rather than the default Xenomai, and you can set up RTXI in non-real-time mode using the POSIX interface. You may also direct RTXI to libraries/packages in non-standard locations. The full configure options for are below:

configure' configures RTXI trunk to adapt to many kinds of systems.

Usage: ./configure [OPTION]... [VAR=VALUE]...

To assign environment variables (e.g., CC, CFLAGS...), specify them as
VAR=VALUE.  See below for descriptions of some of the useful variables.

Defaults for the options are specified in brackets.

Configuration:
  -h, --help              display this help and exit
      --help=short        display options specific to this package
      --help=recursive    display the short help of all the included packages
  -V, --version           display version information and exit
  -q, --quiet, --silent   do not print `checking...' messages
      --cache-file=FILE   cache test results in FILE [disabled]
  -C, --config-cache      alias for `--cache-file=config.cache'
  -n, --no-create         do not create output files
      --srcdir=DIR        find the sources in DIR [configure dir or `..']

Installation directories:
  --prefix=PREFIX         install architecture-independent files in PREFIX
                          [/usr/local]
  --exec-prefix=EPREFIX   install architecture-dependent files in EPREFIX
                          [PREFIX]

By default, `make install' will install all the files in
`/usr/local/bin', `/usr/local/lib' etc.  You can specify
an installation prefix other than `/usr/local' using `--prefix',
for instance `--prefix=$HOME'.

For better control, use the options below.

Fine tuning of the installation directories:
  --bindir=DIR            user executables [EPREFIX/bin]
  --sbindir=DIR           system admin executables [EPREFIX/sbin]
  --libexecdir=DIR        program executables [EPREFIX/libexec]
  --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
  --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
  --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
  --libdir=DIR            object code libraries [EPREFIX/lib]
  --includedir=DIR        C header files [PREFIX/include]
  --oldincludedir=DIR     C header files for non-gcc [/usr/include]
  --datarootdir=DIR       read-only arch.-independent data root [PREFIX/share]
  --datadir=DIR           read-only architecture-independent data [DATAROOTDIR]
  --infodir=DIR           info documentation [DATAROOTDIR/info]
  --localedir=DIR         locale-dependent data [DATAROOTDIR/locale]
  --mandir=DIR            man documentation [DATAROOTDIR/man]
  --docdir=DIR            documentation root [DATAROOTDIR/doc/rtxi]
  --htmldir=DIR           html documentation [DOCDIR]
  --dvidir=DIR            dvi documentation [DOCDIR]
  --pdfdir=DIR            pdf documentation [DOCDIR]
  --psdir=DIR             ps documentation [DOCDIR]

Program names:
  --program-prefix=PREFIX            prepend PREFIX to installed program names
  --program-suffix=SUFFIX            append SUFFIX to installed program names
  --program-transform-name=PROGRAM   run sed PROGRAM on installed program names

X features:
  --x-includes=DIR    X include files are in DIR
  --x-libraries=DIR   X library files are in DIR

System types:
  --build=BUILD     configure for building on BUILD [guessed]
  --host=HOST       cross-compile to build programs to run on HOST [BUILD]

Optional Features:
  --disable-option-checking  ignore unrecognized --enable/--with options
  --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
  --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
  --enable-shared[=PKGS]  build shared libraries [default=yes]
  --enable-static[=PKGS]  build static libraries [default=yes]
  --enable-fast-install[=PKGS]
                          optimize for fast installation [default=yes]
  --disable-dependency-tracking  speeds up one-time build
  --enable-dependency-tracking   do not reject slow dependency extractors
  --disable-libtool-lock  avoid locking (might break parallel builds)
  --enable-xenomai        build the Xenomai interface
  --enable-posix          build the POSIX non-RT interface
  --enable-debug          turn on debugging
  --enable-comedi         build the comedi driver
  --enable-analogy        build the analogy driver
  --enable-ni             build the ni driver
  --enable-clampprotocol     build the clamp protocol module (default=enabled)

Optional Packages:
  --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
  --without-PACKAGE       do not use PACKAGE (same as --with-PACKAGE=no)
  --with-cppunit-prefix=PFX   Prefix where CppUnit is installed (optional)
  --with-cppunit-exec-prefix=PFX  Exec prefix where CppUnit is installed (optional)
  --with-pic              try to use only PIC/non-PIC objects [default=use
                          both]
  --with-gnu-ld           assume the C compiler uses GNU ld [default=no]
  --with-x                use the X Window System
  --with-Qt-dir=DIR       DIR is equal to $QTDIR if you have followed the
                          installation instructions of Trolltech. Header files
                          are in DIR/include, binary utilities are in DIR/bin.
                          The library is in DIR/lib, unless --with-Qt-lib-dir
                          is also set.
  --with-Qt-include-dir=DIR
                          Qt header files are in DIR
  --with-Qt-bin-dir=DIR   Qt utilities such as moc and uic are in DIR
  --with-Qt-lib-dir=DIR   The Qt library is in DIR
  --with-Qt-lib=LIB       Use -lLIB to link with the Qt library
  --with-rtai-config=FILE location of the rtai-config program

Some influential environment variables:
  CC          C compiler command
  CFLAGS      C compiler flags
  LDFLAGS     linker flags, e.g. -L if you have libraries in a
              nonstandard directory 
  LIBS        libraries to pass to the linker, e.g. -l
  CPPFLAGS    C/C++/Objective C preprocessor flags, e.g. -I if
              you have headers in a nonstandard directory 
  CPP         C preprocessor
  CXX         C++ compiler command
  CXXFLAGS    C++ compiler flags
  CXXCPP      C++ preprocessor
  XMKMF       Path to xmkmf, Makefile generator for X Window System