Most of the pain of taking over the maintenance of Crypt::Rijndael was solving this same problem. In that distro, see the rijndael.h file to see what I've done. Basically, I test for each operating system, architecture, or compiler and do the special thing for it to define UINT8 and UINT32. A lot of people have helped by sending in the magical #defines and right header files for their system. Also google my Crypt::Rijndael posts on use.perl for threads asking the same question.

I now have several virtual machines set up so I can test on the problem systems, mostly Solaris and various Windows environments. That helped a lot since I didn't have to guess if something might work and send it off. I could paly with the system. I also used HP's Test Drive stuff to check VMS. Too bad Sourceforge turned off their compile farm, which is the only reason I was still using them. ;(

Good Luck :)