The 'Original' S90 and underwater housing WP-DC35

I'm considering getting an underwater housing for my little S90. It's a great little camera (the original pocketable quality powershot!). I'm going on a holiday though and would like to try some underwater photography.

Interestingly, getting a new WP-DC35 for my S90 seems to be the cheapest way for me to do that and have acceptable image quality too (and RAW ability to boot).

Any recommendations regarding setup of the camera, tips and trick are welcome because I don't have much opportunity to experiment.

My S90 has been modified with Richard Franiec's Custom S90 Grip and Lensmate control dial ring. Can I leave these accessories on when I want to use the underwater housing or do I need to strip them off?

Many thanks.