Peter: that's what we call a Vax: wash & dry vacuum hoover.

Don't worry about losing the creases: you aren't going to be flat-packing it and putting under mass weights for a long period: it'll be fine.

The thing I would be worried about using a vax-style cleaner is if the carpet shrinks whilst drying. Ideally you could fit it still slightly damp & allow to dry out when fully fitted..but do you really want to fit a wet carpet onto the metal floor unless you can guarantee it will dry thoroughly?

Or dry brush it with a scrubbing brush and use a small amount of water/stain remover on stubborn areas. Normal carpet cleaner will work a treat (spray bottle variety) and won't wet the carpet too much.