Ryan,
Your best bet is to do it from the CLI, and the syntax will look like this:
aggr create little_aggr -t raid4 -n 2
where "little_aggr" is the name that you want to give it.
From there, on an existing system you can move all of the data of the root volume over using this procedure:
https://now.netapp.com/Knowledgebase/solutionarea.asp?id=kb6360
I have done it before and it works like a charm.
Best of luck!
TC