i bought an old plusnet hub one, opened it up. soldered wires to the wee vias, and while trying to strip the wire at the other end, pulled on it and ripped the via clean off the board. too small to try to repair.
Thank goodness they are so cheap. i hope i learned my lesson.
live and learn I guess 
In this specific case, don't solder at all, even if you don't rip the via off, the via is very sensitive to heat as well.
Personally I used two narrow strips of tin foil, isolated it with electrician's tape (everything but the tips coming into contact with the via), soldered the rx/ tx cable to these strips on the other end and taped them into place on the empty/ non-populated area of the PCB. During the procedure just keep them pressed down with a (rubber gloved-) finger; take gnd from a safe place (near the connectors).
Yes, this means keeping your finger pressed down firmly and not moving for around 50 minutes, while operating the computer with one hand only, but it makes the procedure much safer.
If you need to do it more regularly, build some fixture with well-aligned pogo-pins, but that's overkill for doing it once or twice.
Yeah I also damaged a hub-one during the soldering process and had to throw it in the electronic shop recycle bin