You don't say what switches you are using, but to get over this bounce problem, try replacing them with optical switches of some sort. Mine are laser detectors, fixed at the limits. I have two lasers on the carriage, and when they shine on a detector the detector sends a Ov signal to the computer. The lasers were £10 each and the detectors were in the order of £1 each (possibly less, I can't remember) The beauty about it, there is no big mechanical obstruction on your lathe bed to get wiped out, and you can, if you wish have both homing and limit detectors run by each laser.
The detectors are schmidt trigger types, which give an instantaneous signal (no bounce), and I find the accuracy very good, even with cheap non-focused lasers (to less than 1 thou).
I had some pictures, but have lost them - if you would like to see the idea, I will post them again.