I would suggest using at least half an hour of that time to show your workmates how to use Perl::Critic (or Test::Perl::Critic).

Set P::C on a quite high verbose level and provide each workmate with a copy of Perl Best Practices.

Since a single day is a rather short time for training, with P::C you will them a valuable tool with which they further their knowledge on their own as well as check their code for common mistakes and problems.

Just my 2 cents...