If you're the Emo
You want a low hp set, bond the dhuum person (either the rit or the necro) and your stone, get in position and pop the stone a few seconds before the last person enters the room, for a clean glitch just face the dhuum person and the stone will sit at a good position unless it runs forward. For a solid glitch you want dhuum to be parallel to you with the stone exactly in the middle, here is an example of a clean glitch:
Green being you, black being the stone, and red being Dhuum.
This is an unstable glitch, don't expect it to hold (especially if someone moves), be wary of where Dhuum pops up, because he will run at you in that direction and you may need to adjust your position:
Glitching on a turtle
Turtle is by far the easiest stone to glitch on, simply stand in the middle of the green ring of the turtle.
Glitching on a rider
This is a little trickier because riders have a smaller green ring, but still very simple. You want your green ring to be a little past the edge of the dream rider's green ring, like so:
This is the perfect place to glitch with a rider and will be a very stable glitch.
I would also recommend infusing the rider on judgement so the glitch holds.
Dhuum as a soul
You have 5 skills, rest, spiritual healing, encase skeleton, DP removal, and fury. At the start you'll need to assess the situation and adjust your routine accordingly.
If Dhuum glitches instantly
Very simple, just spam rest, auto attack dhuum and heal anyone taking damage (watch for unbonded squishies at judgement, mesmers, eles, etc) if no-one is taking significant damage, heal the stone on judgement. When the glitch is stable move forward and stand on the emo.
If Dhuum doesn't glitch
There will be champions and minions running around bashing on everyone, spam heal whoever is tanking the champion and auto attack it. Under honor it will die very quickly. If it wasn't an instant glitch it is unlikely everyone will be bonded so be especially careful during judgement, heal anyone taking significant damage. If Dhuum uses Weight of Dhuum on the stone, heal it and use 4 (DP removal) on it. If Dhuum runs around, run through the stone to get on the opposite side of dhuum, if you go around dhuum will just follow you around. If he drops, prepare for him to pop up again as quickly as possible, dealing with all the minions and getting the stone in position. Rinse and repeat until you have a stable glitch, then continue as normal.
AND BE SURE TO FUCKING HEAL PEOPLE