I've been trying to think up a feat similar to the Ascetic Rogue/Mage type feats out of 3.5 Complete Adventurer except for Wizard/Alchemist. Something like 2 Wizard levels count as 1 Alchemist level for purposes of Extracts--or 2 Alchemist levels count as 1 Wizard level for purposes of spellcasting.
Any ideas/suggestions?
I'd suggest looking at SGG guide to feats of multi-classing.
Unfortunately I only see one alchemist feat in there and it has a pre-requisite feat/ability that's not described in the guide :(
That and the feats seemed mostly aimed at anti-multiclassing, which is not what I'm going for.
Make a custom archetype. Here's one now.
Or, roll your own; there's a thread around here somewhere with decent rules on the subject, and from what I've seen they'd be happy to critique it.