I can't remember the status of the IR-Front end document, and it is stapled
to something we got under NDA from National. So I don't think I can post
it. Sorry.

The TEMIC TFDS series irda parts would probably work (I think they were 
taken over). See http://www.vishay.de/irdc/irdc.htm for example.

The HP HSDL 1100 seems to be common too, but it requires the two rx line
connection so may be harder to rework.

I think Sharp also do an IRDA module that would work, but I don't have 
a reference number.

If you want to look more closely at what IR is being seen by the superio
I think it has a capture mode that returns raw data, or the on/off time
of the IR.

Mark