How to have a New Lead Automatic Partner Assignment?

I've seen a couple of threads hinting at this, but they seem to stop at providing any solutions. We are using a network of manufacturer's reps in addition to a small team of inside sales reps. I've defined territories based on our manufacturer's reps regions and have entered them as partners. I'd like to assign new leads (from on online form) to the partners automatically. It looks like it would have to be a script, but doesn't look like it's possible to access the territory record from a script. Anybody have any thoughts on if this is possible or if I'm thinking about this