Squeegy,
Yep, Everytime I have had to true one of these up, or replace a spoke, I have just used an adjustable spanner on the nipples (corresponding to the spoke I wish to tighten).
I think that you are unluckier with a bend in between spokes - this one would require some "attitude adjustment" using two blocks of wood (to lay the rim on) and a soft mallet to bang on the rim to flatten it out. Tightening and loosening spokes will not produce a satisfactory result.
Make sure you mark the high point of the wobble (so to ensure that that is the force of your "adjustment"), and that the blocks are placed to isolate the wobble/bend only.
Patience will be the key here - but it can be done.
Good luck, and don't try this one under the influence of alcohol - you'll lack finesse!