As Tari stated the build I have uploaded is Windows Only, but I do most of my libfxcg work on linux. I could throw together a script to compile gcc and binutils but following
http://wiki.osdev.org/GCC_Cross-Compiler#Step_1_-_Bootstrap is pretty simple, just replace i586-elf with sh3eb-elf and set the prefix to where ever you want to toolchain installed.
Then just update the PREFIX line in the makefile and convert the \ to / where needed. I used \ because all the exe's work fine with both but window's del fuction uses / for options so I just used / to be consistent. That said the latest Makefile and libfxcg.a at
http://jonimoose.net/calcstuff/prizm/ have been updated to be a little nicer. Just drop libfxcg.a in PREFIX/lib and replace the existing makefile with the updated one and you should be set. You'll still need all the headers from the windows only release though.
When I make my next release I'll be sure to include a stripped down, only what you need version.
Oh and you'll need to build a copy of Tari's mkg3a as well, he should be able to link to the latest source for you.
EDIT: Oh contrary to what Tari said and I am working on getting newlib built for newer versions but one of the downsides of using newlib is you can't easily override libc functions with your own version without messing with the build system. I already have programs linking against it and using libc functions like snprintf but there appear to be some glitchyness, possibly encoding related, I have yet to figure out.