http://spokaneteamfortress.com/monster_mm_i386.tar.gz
In case you want to just download my fixed monster plugin. This was ported from botmans and I added in support for a couple extra monsters. If you want the sources...
http://spokaneteamfortress.com/monster_src_lnx.tar.gz
Also GCC 2.96 works fine for HLSDK/Metamod compiling. I believe any sub 3.0 version will work as well. Just edit your metamod Config.mak or was it the makefile itself and comment out the gcc version deally...