dual boot different platforms from the same partitions in a host

[Tom Vajzovic <vizaviza@yahoo.co.uk>]

Hi

I would like to dual boot Linux i386 and amd64.

My amd64 processor will run either quite happily, but not at the same
time.

I think perhaps that I  need separate /usr partitions, and I hope that
at least /home could be shared, and maybe /etc and /var as well.

The reason to do this is that I sometimes want to run binary only
libraries and apps that are 32 bit, but the rest of the time I want to
use the full 64.

How do I go about setting this up?

TIA times a million!

Tom.x