i did it to a optical wheel mouse while back, but undid it, it was way less responsive, i used the 3.7 v radio shack LED, problem is the red one included is most likely ~2v, so the blue isn't as bright, afte the mod, it worked fine on white paper and "regular" mousepads, but was erratic and useless on black & white everglide pads... just a warning to those who wish to try, i think the microsoft line takes the mod better because the casing is solid colored... the translucent logitech seemed to "leak" too much light as well...