Robin, I have one on my TSA102 and it works a treat. Just order it specifying your type of scope and everything fits.
Once you calibrate it your away. The algorithms used for focus are super accurate and like someone has already mentioned, it remembers the focus position from last use. I could quite safely say that if you go the robofocus way you wont be disappointed. Also greg pointed out that its a serial interface and so a usb to serial converter is required. There are builds of these that are not reliable, sometimes the hardware requires physical CTS RTS lines.
http://www.dontronics-shop.com/easys...0cm-cable.html I use this brand of converter with 1m and 10m versions available its handy.
Good Luck