OS X Virtual Machine

Hello, once again!

I have a 2011 iMac that came with Mountain Lion. I'm enjoying the OS, but there were a few features in older versions of OS X, that I need when doing work.

Is there a way to install OS X (maybe Tiger) on a virtual machine of choice? If you can, please tell me the software I should purchase, the step-by-step process, and any other information I should know.

Thanks!!!

By the way, I still have my old copy of Tiger from my old Mac. I couldn't install onto a partition, because the iMac can't install an OS older than the version it came with.