Shameless plug here, but if you're interested in installing the platform but don't want it clogging up your dev environment I've created a snap project skeleton that will do it for you with Vagrant and Chef.

http://johnbender.us/2011/03/05/snap-setup-from-scratch-the-...

Snap is the only extra install and you can quite easily alter the haskell platform version in the Vagrantfile. I'll be updating this tonight when I get home if you don't mind waiting.