The injury-plagued defender has just returned to training.
"He is back training with us, but he doesn't train every day in case his knee starts to swell up again," said O'Neill.
"Wes is desperately trying to do a couple of successive weeks' work without taking any break, but so far he has been unable to do that.
"He has been training more often and consistently than he has at any other time in the last 13 months, though.
"He wouldn't be in any position to start a game in the foreseeable future, though.
"Once we get to the end of the season, it will give him a chance then, if he is still OK, of having a proper pre-season and then who knows.
"It's just a case of treading carefully with him, but there are some encouraging signs."