I would also like to know what is the best way to gain GD's dex up. Atm it's 65....
So I can at least tell you how I have been doing it.
For GD I create a macro to Res and then a quck mind blast to kill. Loop th macro until skills are down to 0. Skills will show as '--' once they drop below 10. They will continue to drop even though you will not be able to see, and the same goes for gaining skill; they will raise but you won't be able to track until they get above 10. (dumb, I know).
Once you killed your dragon down to 0, create a macro to cast curse on it. Also, with the little code that pro hunter shared with us above, I added some time in to pause. You want to maximize the dex gains on the way back up to 100 skill. I am able to get anywhere from 10-20 dex increase overnight.
Be sure to add in feeding your pet to the macro. A loop that runs for 30-40 minutes and then feeds will do the trick.
Resist training is the easiest way to be able to macro this so once the pet gets to 100, I don't bother with melee gains unless I am only a few points away from max dex. I will kill pet down to 0 and start over with resist.
For Cu's the kill macro has to be timed well since they self heal within a few seconds when they are high skill. I use a Res/Fireball macro to do this. With Cu's I will train up their healing (and anat goes up with it) first since they get good gains for it. I do healing first so they don't resist me casting poison on them which i use when there skill in healing gets higher. My macro I adjust along the way up. I don't have any specific skill levels at which I do this since I am still experimenting. But, I start with a few fireballs every few minutes(currently at 4 minute intervals). Once they can start reliably healing, I add a poison into the casting, so Poison, Fireball, Fireball,, etc. I adjust how many fireballs according to their skill level too.
Once healing is done, I will move on to resist. It seems for cu's starting with decent dex(85+) I only have to kill them down to 0 twice.
As an experiment, I tried just going into lich form and letting the Cu (who started at 0 skill) heal me. I only gained 2 points dex overnight so won't be doing it that way again.