f&l / ultrafire bike light mod

ive developed this light obsession bla bla bla

anyway ive purchaced 2 flashlights

a fenix L1P - a general replacement for minimag incan

a j&l / ultra fire cr2

well the story goes im also making a mr11 incan light for my bike all home fab
then the j&l arived and i was impressed with the light and also how cool the case looks... a lot nicer than my dodgy bit of ally tube with an mr11 stuffed in

so i was wondering...

could i put a genuine luxeon in there like a lux v or a III
and run a wire into it (eg loose the cr2) then power it from external batteries

ok im not looking for a physical reason why not

so i need to know....

the current "engine" is probably some none generic thing - can i desolder the actual emmitter and replace it with a higher power model - will it fit and will it work?

will this cause heat problems?

what voltage do i need to run the lux at its optimum without ruining it?

can i do all this with a normal electric soldering iron?

most of the terminology etc i have picked up from cpf but i really am a total beginner with only limited electrical knowledge

(I have completely dismanteled the light just to check the engine is removable etc and it is)

thanks

Alex