Answer:
I've got a four year old right now that I took in a year ago. She wasn't socialized at all and was afraid of absolutely everything, even doorways and normal footsteps.
LOTS AND LOTS of love and one-on-one time. The dog needs to know that ANY interaction with people is going to be a positive thing. Make sure that it is.
Constant interaction is really important, but don't force it.
Dogs don't have very good long term memories, which is a blessing: mine has turned right around and is is now a friendly, outgoing sweetheart of a dog. Once yours experiences nothing but positive interaction with people she'll (he'll) come around, though there may be some lingering traits or fears that you'll need to work around. Those may never go away.