I just took a quick look into it. Seems that your problem is not compiler version (btw, you'd also need compat-gcc-32-c++ if you want to compile the thing with the old version of compiler). Looks more like version of mysql header files. Your best bet would be to either contact author(s) of aspseek or ask on mysql (devel?) list what to do with program that expects old header files if you attempt to build it against new(er) mysql.
well in the end it did work using
aspseek1.2.10 gcc3.2.3 mysql-4.1.14
and the exact same combination of aspseek and mysql did not compile using gcc3.4.4 - So not sure what the exact issue was but i got there in the end!!
thanks