[TxMt] Change version of perl called by TM?

I've installed a few perl modules at the command line but they are not seen in TextMate. What happens is that if I run code (Cmd+r) from within TextMate that calls a module that I've installed, TextMate can't find it: Can't locate LaTeX/Driver.pm in @INC...

Investigating this I find that TextMate is calling Perl 5.8.8 whereas, at the command line, perl -V tells me 5.8.9. So TextMate is calling a different perl version to the one the modules are installed under.

How do I change which perl version TextMate uses?

I've had a look in the bundle at the Run Script command and that references ENV["TM_PERL"] but I'm not sure where this is set. Can anyone help with this?