Yes, that would be easy enough to do provided you're able to get by using the pre-soldered ends that were removed from the mini-XLR's. Otherwise, if you need to trim one of the wires, then as Brian says, I recommend pre-tinning it using liquid flux and a proper solder pot. Technically the enamel insulation on the litz wires is "solderable," but if you just solder it in place, then all the residue from the insulation gunks up the solder joint. When tinning litz wire in a solder pot, you keep the wire moving so that the residue is left in a "snail trail" behind the wire so that when you come up out of the pot, you've got a nice clean tinned end.
All to J-STD-001 Class 3 requirements?