To get to the Mortein Wall, park as for South Central, and walk down the same slightly overgrown path. Continue straight ahead for about 50m until a small crag appears to the right of the path (this is the Bakery crag). Walk along the base of the cliffs past the Bakery, Bartondale and Rosies crags, until a tall vertical wall appears with a thin looking orange streak in the middle ("Jock Itch" 23).
As its name suggests, the Mortein Wall sees a bit of insect action, so bring along the insect repellent.
A note about grading: I had heard that Nowra climbs were generally (and in some cases severely) undergraded. From my (somewhat limited) experience, I'd say that the grades are all pretty fair, being comparable to Blue Mountains grades (Mt Piddington is the crag I usually measure against). In any event, if you're just leading Sydney 16s, a Nowra 16 might leave you hanging from the sharp end of the rope.
The guidebook for the area is the "Rockclimber's Guide to Nowra & Wollongong". There is also a "Rock" magazine update available, which is well worth getting.