There are several ways to obtain the fsp source distribution please take a look at Section 1.7
At the moment we provide only RPM for RedHat 7.3. You can download the RPM file from the sf.net download page or from wrack.telelev.net. wrack.telelev.net provides the rpms in a apt-rpm usable way, for more information about apt-rpm and the packages on wrack.telelev.net take a look at http://sven.stormbind.net/aptrpm/ If you're running other rpm based distributions you can try to rebuild the source rpms.
After download you should be able to unpack the source tarball, change into the source directory and use ./configure make su make install