In Mysteries Revised there is:
A path to immortality called living ghost (IIRC) which is obviously
relevant to necromancy
There is also the spirit familiar virtue which can be appropriate for
Hermetic empowerment, which is a virtue that allows you to trap a
spirit in an enchanted device and use it to power ritual effects
(ritual effects in an enchanted device, that's not bad) this can be
done with any spirit, ghosts included.
That's all that come to mind from Mysteries revised but I wouldn't be surprised if I had forgotten at least as many as I remembered.
Naturally the object of the original research rules is to allow the character to do any sort of original research so you shouldn't feel obligated to repeat what's present in the rules someplace else.
I think that a pathway for necromancy would be to develop a way to steal the fatigue levels of others (not just remove them ala the perdo corpus spell that I can't recall the name of, but take them for your own). Hermetics have come close to this being able to give their levels to others but taking them from others breaks the limit of energy. Yet the folk witches from Hedge magic revised can create potions to provide fatigue levels from magic and followers of the path of energy (from Guardians of the Forest) can grab fatigue levels from nature so we know that this limit is breakable. (For more badassity you could also work up integrating life boost or life linked spontaneous magic which have a very similar theme and would be especially complementary powers).
That's dealing with personal energy rather than dealing with dead creatures so perhaps necromancy wouldn't be the best description. Actually forget that whole idea, it's not about the dead.
It seems to me that since hermetic magi can make more or less any sort of an effect that can be described as "create, perfect, control, change, learn about, or destroy" Necromancy is pretty well covered. You don't need so much research as you do engineering. But making cool spells and devices with the tools that you already have won't win you everlasting fame, even if it is the sensible thing to do. Lets see if I can come up with a better idea...
How about you summon a ghost and then make a copy of it's mind to have available at your beck and call? Enchant a device Cr(In)Me device that creates a copy of the mind you've summoned and then keeps it saved forever as a constant effect. Crap, you don't need research to do that.
Harvesting vis from the deaths of creatures? It's dark, it will probably get you damned to hell and marched but it's at least something that can't be done with hermetic
"technology" as it stands.
How about learning to contact souls in heaven, twilight and/or hell? That's necromantic, arguably noble, and the sort of incredibly difficult achievement that will win you everlasting fame.
Another thought is to give a Frankenstein style monster a soul. How about creating such a creature by including a live child destined to be stillborn, or to die with his/her mother before he dies and thereby skirt the edge of the limit of the soul?