Embedded application on PS3, dev questions

Can anyone answer a couple of questions for me about developing for
the Cell BE on the PlayStation 3?

My big question is: If I install FC5 PPC (or some other Linux distro),
what will I need to add in order to be able to build a program that
accesses the SPEs; is there a walkthrough on this?

Secondarily: Is anyone aware of a USB audio input device that will
work nicely with the PPC Linux kernel?

Google finds roughly ten zillion pages of people gushing about how
they can see a Gnome desktop on their PS3, but not much in the way of
useful content.

My intended application is not very challenging: it's simply to take a
44.1kHz audio signal input and use one of the SPEs to run a 512-bin
FFT and display the spectrum onscreen.