My Tufty is going through this now as well
- he hates wet food so my vet has given us Hills SD which is the dissolution formula in a dry kibble.
Tufty loves it, it has a thirst enhancer in it which helps them flush through the crystals, expect to have all your cats munching happily away on it as well - seems irresistable!
Pop some newspapers around so he's not trying to pee in the litter tray all the time, it's painful and may cause him to hate his tray in the future.
Tufty's wee is almost back to normal after two weeks on the SD diet - vet wants him to stay on it for 6 more weeks, then coming down to CD for a while afterwards.
You can get Hills SD on-line from VETUK, if your vet doesn't stock it - no you don't have to be a vet or have a prescription for it.