I'd suggest you look at the following threads:
Milky L1 Info and
Project-M. These will give you ideas on what can be done, and I'm sure that MilkySpit would provide some guidance too. You can also purchase an ML-1 from Milky or send him yours for modding. I understand the bezel in the L1 pictured above is a little difficult to open, especially when compared to the earlier L1 version bezel.
I've owned a UX0K and now a Cree-based ML-1 and loved both. The cree is a little brighter on high and low plus has an incredible battery life. The ML-1's are a specialty of MilkySpit. I've got a P4-WH in my ML-1 and also have a fitted reflector, so I got my choice of tint/output and a reflector vs. the standard optic. I have a great, bright spill and a nice throw too. Do a search under my name and you'll find some outdoor beamshots I did of a few of my lights.
Another option is to wait a few (?) months until the cree-based units start shipping from Surefire.
edit: As a first (and inexpensive) mod pick up an F04 beamshaper from Surefire (opticshq.com, tacticalsupply.com, lighthound.com). It completely alters the beam characteristics providing a soft flood of light.
