I took a 2wd Honda Jazz up there last year - no problems.
Byatts is literally just around the corner/hill from where you access East/West Tower - O'Tooles road.
I went around and accessed it from the South the road was in really good condition and higher up than the Northern side.
As for west tower - I tried to head up Fonthill Road from Byatts/O'Tooles at the southern side and ended up turning around at a creek.
The road wasn't in good condition, pretty mushy and there was an old chain gate that I could have gotten across - If I had my Subaru I would have persisted.
So I went up East Tower and did the traditional Abels route across to West Tower.
Fonthill road looks in good condition looking down from West Tower - so I reckon you can get around from the northern side.
Also of interest on West Tower I found a well taped route heading off to the North / NE down towards Fonthill Road - so I reckon there is a route up from there.