We have at DX a new driver for XM-L
Is a buck driver, accepts from 6 to 18 volts.
It seems to feed 3A to the LED and has 3 modes (H, L, Strobe)
http://www.dealextreme.com/p/6-18v-3000ma-3-mode-circuit-board-for-xm-lt60-emitters-57779?r=43033281
Unknown diammeter....