Well, it seems like what has been will be again, what has been done will be done again, and there is definitely nothing new under the sun! The topic of tap sizes was discussed from 2006-2008, in relation to DW's original 6263 cases. I believe the dimensions hold true for DW's current crop of 6239 cases.
Here's one thread. I wish some of those guys were still here on RWG-Rolex!
The answer is 0.25mm x 0.25 for DW's pushers, and 0.25mm x 0.2 for genuine, Ofrei, and Cousins pushers.