In reply to Cadairmanuk: There was a distinguishable path until about 3/4 of the way up the zig-zags. We just did Number 5 Gully and walked off the tourist path, so we didn't summit. There was no path on the plateau from what I can remember. With crampons, which you have you should be fine.
You can just take a bearing when you reach the plateau, but watch out for gardyloo gully!
BR