How would i go about washing trousers?

If they say "dry clean only", then they really should be. Yes, some things that should be dry cleaned can be hand washed with Woolite. But they never look the same as they would if they were dry cleaned. So maybe the answer to your question lies in where you plan to wear these trousers and just how nice you want to look when you do. You can reduce the amount of dry cleaning needed by simply freshening them up with Dryel (see link), but that's not exactly cheap either.