I actually don't know anything about recording. I only used Audio::Play etc for generating sounds (plug: Audio::LADSPA). On linux (with OSS) at least, you can read the raw data from /dev/audio.

If you can't find a portable audio module that does recording, you could use some portable command line tool that records to wav files and proceed from there. AFAIK mencoder (included with mplayer) should be able to do that.

update: ecasound might also be an option. it has perl bindings, is available for os-x, linux and windows (via cygwin).