If you are nervous about rooting (or, in my case, can't because a custom recovery's not out yet for CDMA), and don't mind clogging up your storage with another ~20MB of stuff, you can just download an ICS imitation launcher from the Play store. Looks almost like the real thing.
For examples, search for "ICS launcher". If you want the lockscreen too, "Go Launcher EX"+"Go Locker"+"Go Locker ICS Locker theme"+"Home Manager"(for swapping ICS in place of Go Launcher) will do it, albeit at the cost of even more storage. Above combo runs pretty smooth on my phone, and the ability of the ICS launcher to customize home screen grid size, I must say, is a sweet feature.