[CentOS] Recompiling source rpms for i386, i686 and x86_64 on the same box?

> For the 3 arches you want they could all be done under mock in a x86_64
> environment. Under

Indeed, I build 32 and 64 bits RPMS on an x86_64 CentOS 5.5 with mock.

In order to deal with the multi arch, I call mock as follow:

setarch $ARCH mock --arch=$ARCH -r <mock config file> --debug $SRPM

Note that I pass the --arch argument to mock, but also had to put
additionally setarch before the actual call.

On a side note, use the CentOS mock (in extras), not the one from EPEL.