The trick with Rwanqa is exactly that: avoid the gully and the waterfalls. For the most part it's a steep, grassy pass - no need to clamber up boulders. I've heard about people needing ropes to pull up packs, but that can be avoided.
The grassy ridge coming down directly below the Black and Tan Wall is your salvation on Rwanqa. Be alert for a small trail which will guide you onto the southern flank, where it starts disappearing, but where you simply ramp onto the crest of this ridge. Follow the crest up as far as reasonably possible, directly below the Black And Tan Wall. From there it's a steep, grassy traverse across to the main gully from where the going becomes easier (no trail).
If you download the GPX file from the downloads section and open it in Google Earth, you will clearly see how the track avoids the main gully. Hope this helps.