What I did a few years back, as per Red Lion, was to install each version in a different folder. I have Crimson version 1, 2 and 3 available which is nice for working with older systems where I do not want to lock the client out of his system or need to preserve it as it was.
What I meant by that is installing an older build of Crimson 3.0 over a newer build of Crimson 3.0 without uninstalling the previous first.