Get one of those long tubes that you buy tennis balls in and pop your roller inside. Fill the tube with your solvent, enough to cover the roller. Close the tin tightly and give it a good shake. Let it sit for a couple of hours. Give it a final shake and then it is ready for washing with soap and water.
I must admit though, rollers are such a pain to clean and they are quite cheap nowadays, I do tend to just throw them away and buy new ones when I next decorate. (Not often)
