On January 25th, I wrote a blog post with instructions on Installing and Configuring VMware Fusion 5.02 on a Mac to do Windows 8 and Windows Phone development. I am following up with a new post on Installing and Configuring Parallels 8 on a Mac to start developing Windows 8 and Windows Phone apps.
1. Download Parallel Desktop 8 (14-days trial version) from http://parallels.com/downloads/desktop.
2. Run the ParallelsDesktop-Build_Number-.dmg package that you downloaded earlier. The Parallels Desktop app starts. Double-Click the Install icon.
Note If you have a Windows 8 bootable DVD, instead of clicking Choose an image file, click the DVD drive that contains your Windows 8 bootable DVD. Then click Continue.
For more info on installing the 90-Trial check this Windows 8 Enterprise Evaluation FAQ http://technet.microsoft.com/en-US/evalcenter/jj552442.