I have taken mine apart to do some maintenance, and looked at the switch. It looks like a power switch from a PSP2000 will work-no guarantees though. I didn't take any measurements with my DMM to determine the switch's continuity in it's "off" and "on" settings.
Had I done that, I'd be able to confirm whether a PSP power switch would work.
Perhaps once the switch is desoldered, a part number might be branded or stamped to the switch.
Motion Computing LE1700 [SXGA+ View Anywhere LCD (LTD121KM2M)|Core2Duo 1.5GHz, Samsung HS08XJC 80GB 5400rpm]
Elitegroup S20II [WXGA, Core2Duo 1.86GHz, WD5000BEVT]
Samsung Q1U/P [Core Solo 1.3GHz, Samsung HS08XJC 80GB 5400rpm]