http://froglet.us/Hobby/terrarium_setup.html

I found this which helps alot. A gravel bottom with a fine screen over top, then the planting soil. Just have to drain the tank every so often if moisture builds up too much.

Seems easy enough. Plant the seeds, UVB light over top on a 12 on/off cycle, Water the grass and things should grow. I was thinking of a fogger on a timer over the tank to provide good moisture without over saturation.