Help! How to clean a stained Silent Night Miracoil mattress?

[CatPower]

Housekeeping goddesses, I need your help.

We have a kingsize Miracoil mattress (layer of memory foam on top), and being the slattern I am, I've "ignored" stains on the surface. By stains I mean sweat (thanks, medication) and, umm, pee (thanks, DS).

I can't ignore the stains any longer but haven't a clue as to what the best way is to go about cleaning the surface of the mattress. Yes, I should have put a protector on top ages ago, I am kicking myself now.

Has anyone successfully de-stained a mattress before? Any tips?