For the record, I have to do the same exact thing to my Logitech G5, I'll keep you guys updated. Problem is, I have some sort of bad karma, every time I try this sort of DYI repairs, something
doesn't quite work as it's supposed to.
Side-story: last attempt was a charging cable for the gf's old Sagem phone. Actual wall charger was almost completely broken, so I used a multimeter, read out voltages on pins (+5 and ground, which match USB), cut off the cable, grabbed a USB cable and cut it, carefully soldered both. Worked just fine for a few days, then "Illegal charger". Re-made the cable twice, no luck. Triple-checked everything, no idea what went wrong
. Gave up as it wasn't worth my time.