(Sorry for the delay, laptop was in the shop.)
This is how I do it.
1. Pick the basil pods one by one as they ripen (by the time the top ones are done, the bottom will have lost their seeds, so you need to go fruit by fruit for maximum seeds.) Place fruits in a small bowl (I use a ramekin)
2. Once dry, roll the fruits between your fingers repeatedly until it appears that what is in the bowl is green dust.
3. Then, take a pinch of the dust and spread it on your palm. Move the seeds around until they are all in one place in your hand. Then, pinch up the seeds and place in separate container. Wipe remaining dust off palm.
4. Repeat until you have gone trough all the dust.
It isn't perfect (besides the seeds, you're also stuck with the little brown nubs the seeds were attached to,) but it does a decent job (better than with mint, at least you can SEE basil seeds).