The bigger question is why bother? I installed an OSX virtual machine on my Windows 7 desktop some years ago, back when you could buy a disk at Best Buy for $30. Otherwise, for the latest version what you'll need to do is go check around and see if you can find it from an illegitimate 3'rd party (a torrent) the new OSX, Mavericks, is free but that doesn't mean you won't be breaking the law downloading a torrent- pretty sure the copyright doesn't allow for distribution by anyone but Apple and authorized retailers. If you have a Mac you don't need a trial- you just get the OS with your computer, and if you're on Windows Apple doesn't allow installation on to non- Apple hardware. On a mac it downloads the OS straight from Apple in recovery mode and handles updates all through the app store, which, on a Windows machine you don't have access to.
To install an OSX virtual machine in VmWare you need to either buy and old copy on EBay or something since they don't sell disks anymore and for Macs the ecosystem is closed- nobody goes to their site and downloads a trial.
