Here is a protocol (the whole enchilada) http://www.livingnetwork.co.za/healingnetwork/mercury_amalgam_removal.html

Doesn't mention too much about what to take prior but everyone seems to be in agreement that lots of C is needed afterwards.

I also believe Andy Cutler recommends chelating not too long after removal. The talks about the 6month organ dump which is made much less severe by chelating.