I think it's going to be hard, so be prepared for a struggle - but not impossible. At the end of the day programming (especially non-cowboy-hack'n'slash coding) is not going to be super-exciting to everyone. This is especially true for people already working in an area which is intellectually challenging and rewarding in its own right.
First of all make the talks and workshops fun in themselves - free food (make sure it's nice food!) and similar treats are a good place to start. Try to inject a bit of humour too and, at least initially, keep them fairly brief and as informal as you can.
Secondly make sure the talks and workshops are relevant. Try not to make them too abstract (even if the concepts being covered are abstract) and if you possibly can at all, ensure that they can try out what's been covered. Even better check on what they've done between sessions and provide positive feedback. If they're not relevant and they're not applying what you've discussed then they will (correctly) view them as a waste of time.
Finally try to introduce some basic coding standards, preferably ones which are not too intrusive in how they currently operate. If you're in the .net world Resharper is a good one to begin with as it will warn about things like naming conventions. You can take that further with StyleCop (which can be integrated into Resharper) - but make sure you customise the ruleset first. If you're not in .net then I'm sure similar tools will exist elsewhere. It's not much, but it's a start.
Don't expect instant results (except for maybe any automatically enforced coding standards) - I've heard 6, 9 and 12 months bandied around for the time to introduce best practices.
I've only flicked through it so far, but there seems to be a fair bit of good, relevant, advice for you in the forthcoming book Driving Technical Change.