Buschpounder, you are in the right section. I did a little of the work for you. Here is where I got alot of confidence I can do this.
https://www.candlepowerforums.com/threads/163902
Simple and foolproof.
Here is another wonderful summary of Icarus's many, many mods. Some complicated, but worth seening the different stuff out there.
http://candlepowerforums.com/vb/showpost.php?p=1044752&postcount=57
Another one of my favorite informational tutorials:
http://candlepowerforums.com/vb/showthread.php?p=2057789
Cydonia gave me the courage to use Micropucks and his excellent tutorial if you want a fast and great looking mod:
http://candlepowerforums.com/vb/showthread.php?t=166995
All the above said. The clones of these that I made while mine were in the mail needed some adjustment to fit tight. On one of the tutorials someone said hit the side a couple of times with a center punch....it did the trick perfectly for mine. The DHS that H22A offeres in the B/S/T forum is excellent and will save you hours of time infront of the lathe....all the dimensions have been figured out....no brainer. Worth your time to get a couple if you already don't.
http://candlepowerforums.com/vb/showthread.php?t=160483
Finally, as shown above there are basically two types of heatsinks, those that fit in the top of the battery tube where the light was, and two, those that use the threads on the inside of the head of the flashlight.
I will be corrected but generally the heatsinks that get inserted into the tube are for single LED mods while everyone uses the screw in kind for the 3 or more LED mods. Sandwich shoppe has the nice one that screws in and out so you can get the smaller reflectors tight against the main lense.
Bob E.