If you grab the MS VC++ compiler, you can use Inline::C in combination with ActiveStates pre-built binaries. Saves a bunch of hassle.

Then again, once you have MS VC++, building Perl yourself is considerably easier anyway.

That said, why read a byte at a time? If your frames are fixed length, read or sysread a frame's worth of bytes and process the buffer a byte at a time. Then you can use Perl's string-wise and, or exlusive or and not to process whole strings together if that fits your purpose. And if not, you can always drop into C for that bit and leave the filehandling to perl.