I've concluded work on my concentrate, whose journey was recorded in the thread, "Progress on XTOL-concentrate". My long report is posted here:
http://www.apug.org/forums/forum223/...ncentrate.html

If you do any home-brewing, especially of PC-type developers, I suggest reading it. In addition to the concentrate, I describe some discoveries I made, and some interesting variations that you might want to pursue.

Enjoy,

Mark Overton