In order to convert a x310 to a Distox, you'll need to replace the main board and solder in a non-ferrous lithium ion battery .
The replacement distox board adds a compass and clino to the x310, as well as a bluetooth module. Its generally industry standard for cave surveying these days.
The conversion will certainly void the Leica warranty, as you'll need to open it up and replace one of the two boards in there. The process itself isn't too difficult, but does involve some soldering.
As I said in my previous message, I'm more than happy to do the conversion for you (I've probably done over 100 in the last couple of years). If you're interested send me an email on ben.t.wright (at) gmail.com.
B