Phil - I've never tried these so do so at your own risk.
I've heard of people putting a lightbulb above it to slowly dry the paint. As long as it didn't get too close and dry it too fast this might work.
I've also heard of people using hairdriers set on low... I would worry about this as it might cause the outer layer to dry leaving the interior uncured, that could lead to hairline cracks in the paint.
A fan might work some, I don't know... this would be a safer bet if you were to try anything.. how's the humidity where you are right now? I know once I had this happen when the humidity was high. (well higher, it's always high here haha)
If it were me I would try to wait it out, I know that sux for an answer, as I know for myself I am the most impatient person in the world when waitinf for something to cure... but it's probably the most safe for the paint... except maybe the fan.