The method I have been using is as follows (though it is unacceptable slow.)
There exists a large chunk of ice protruding from the south side of the central node. With a little jumping, you can reach a ledge that goes around the entire protrusion, allowing you to LOS players who are actually at the central node. It should be noted that the southernmost area on that ledge is technically not part of the central node, so motion about that protrusion will result in "Jedi Sage Poniesvista spotted near Central Assault" spam.
On this ledge, there exists a small notch in the protrusion where you can position yourself such that no knockback will knock you off the ledge. In fact, that position seems to be bugged because when you reach it you appear to sink into the ground a little bit. In this position, the number of Imps that can reach you is limited by the rate at which they can traverse the ledge, because of the peculiar line of site at that position, and by the Imps' concern that you may knock them off.
The trick is to get them to come for you, get to that safe spot without dying, then knock off whoever is dumb enough to come for you. The fall will almost always kill them (though there is one place where if they're super lucky they'll land at 1% hp).
My initial success rate with this strategy is very high, but they wise up very quickly. I pose no direct threat to them when doing this, I'm not able to loot items with this strategy because I need to maintain close proximity to that protrusion, and what I am trying to do become abundantly clear the first time I do it. As such, they just ignore me, leaving my kill/hour rate around one per 5 minutes.
It should be noted that when you first approach Central Assault to try to get to that protrusion, you are at great risk of dying. If you get overrun and end up dying while up on the protrusion, my observation has been that the Imps have actively attempted to prohibit me from reaching it again. This limitation can be overcome using stealth, but I don't have that.