Sully was collecting shots from Hans in a routine training drill when one caught him right on the end of the thumb, leaving the Scottish international keeper in agony.
After a short wait to see how the injury responded, Sully had surgery and, after that, time was always going to be the only healer. However, a recent visit to the specialist offered encouragement to the 32-year-old.
"I'm getting on very well," he reported. "I went to see the specialist last week and he's really pleased with it.
"Unfortunately with broken bones, it's more time than any treatment you can have. It coming on really well though.
"What we did first of all was put it in plaster to see how it responded. To be honest, I don't think many surgeons like operating if they don't have to.
"It was touch and go when I went to see him and we gave it a week to see if it would improve, but it did need surgery.
"I had some pins put in, but they have come out now and they straightened up and the bone has knitted back together."
Sully is able to keep up his fitness at the training ground and says he is 'ticking over' while he waits for the go-ahead to start his comeback.
"I've been on the bike and stuff and the specialist says I can do pretty much anything really - anything bar goalkeeping!
"I've got to see him again in a few weeks and it just depends on what he says then. If he says it's alright I can start again.
"I hope it's before Christmas, hopefully long before, but we'll see what he has to say and take it from there."
Neil Sullivan revealed that he is making good progress in his recovery from a broken thumb, sustained in a training ground exercise with coach Hans Segers.