How do I build i386 arch on Athlon 64?

[Gary W. Swearingen]

I'm baaaaack... with more problems, naturally. New CPU & motherboard,
and now SCSI interface fails, CDRW fails as ATAPI or SCSI, PCI
parallel card fails, and too many wanted ports don't work on amd64.
I hope an i386 OS will work better and I can work the amd64 problems
at my leisure.

So how do I build a i386 system on the amd64 system?

I've tried passing ARCH=pentiumpro to make and also tried putting
pentiumpro in /etc/make and tried building a cross-compiling gcc34,
but I'm not having much luck.

This seems like it would be a FAQ, but I didn't see anything helpful
in the handbook or faq or groups.google or the make files.

Thanks.