AW: Multiple RT3 Instances on 1 box?

Hi,
we have different instances and even different versions of rt
running on one machine. 1.0.5, 2.0.11 and 3.0.4
So every rt has its one url like
rt-support.host.com
rt-development.host.com

One Apache is listening to port 80 and handling lots of
virtual hosts via mod_proxy and ReWriteRules to the other
instances running on ports like 13000, 13100, 13200, …

All of them work fine, the only problem are the PERL Modules.
When I installed rt 3.0.4 the CPAN module HTML:Mason was
updated to 1.20 so our rt 2.0.x were not running anymore
because they need HTML:Mason 1.05.
We had to downgrade the Parser Module to get everything back.

Ritschi =B-)