Some ectomancers may even be able to access a skill from a ghost's skill-set, in an act somewhat like voluntary possession; here, the skill acquired is limited by the level of skill the ghost possesses, and the value of the skill rating is added to the complexity for the binding spell.
It reminds me of the Necroscope series by Brian Lumley. The protagonist, Harry Keogh, has the ability to speak with the dead; because he is willing to speak for them and teaches them how to speak to each other they give him knowledge in return. He befriends the ghost of a soldier who teaches him how to fight; for money he writes stories that are told to him by ghosts, sometimes they are the work of famous dead authors and sometimes they are the life stories of the dead; he eventually learns how to teleport from the ghosts of great scientists and mathematicians (though that might be a bit too much for the DFPRG universe).
That could be done either with rituals or, if the GM agreed, perhaps you could use the beast change rules to swap around some key skills as they possess you. Perhaps something like this:
[-2] Ritual - Ectomancy
[-1] The Sight - I see dead people
[-1] Beast change/Spirit Swap. - affecting:
[-3] Modular abilities (stunts only)
This would be suitable for a chest deep character that can summon, talk to and dismiss ghosts as a ritual. Plus they can change their knowledge based skills and gain up to 3 stunts as a supplemental action. If I were the GM I'd allow it as long as:
-Beast change didn't affect endurance or might, having the knowledge and skills of a wrestler doesn't mean you have the muscles.
-You chose a number of personas up to your contacts (or perhaps lore) that you could adopt and they'd generally have set stunts and skill changes already. For instance Black-Ops soldier may give you superb fists, athletics, stealth and intimidation, plus stunts to match; Famous Actor may increase your presence, rapport, empathy, performance and deceit, plus stunts, etc.
Hmm, this could be a fun character