R help - Feb 2011 - R5 multiple inheritance

Hi all - 

Is anyone aware of any solutions (or workarounds) for R5 classes that allow
multiple inheritance? Alternatively, if anyone has ideas about how where I may
be able to start, I'm willing to delve into dark magic. It's presently
possible to give multiple superclasses in contains, but method dispatch only
behaves correctly for the first of them. I don't *think* this has changed in
R2.12.2 - I'm checking into that now.

Regards,
Rob