I did one about a month ago and it came up brilliant. It was Laura Ashley and dry clean only in situ and thanks to a short training session with Jamie from Cleaning Systems UK, I was able to do it and do it well. £180 well earned for two 3 seaters. I used the dry, wet, dry method.
You need to get some Prochem Dri Pro, a trigger sprayer, gloves and a respirator mask. Some Chemspec Fast Drying Upholstery Shampoo (FDUS) is useful too.
You mist on a layer of Dri Pro, agitate and towel. Vac it with your upholstery tool.
For heavily soiled areas you then apply some of the foam from your FDUS and agitate then towel. Vac it with your upholstery tool to get rid of the moisture.
You then re-apply a layer of Dri Pro to repel the moisture from the FDUS, towel and vac.
As Shaun said, using a turbo drier speeds up the drying process and is recommended and only work on one panel at a time when cleaning.
Its a time consuming job but worth it when you see the results. This was for a posh customer of mine and they were raving about the result.
I hope that helps.
Linds