Steve, I would not recommend installing casters on the DeWalt stand. The stand will be unstable and it will raise the saw to high to work comfortable, for me at least.
The Woodcraft store that I teach at installed casters on the DeWalt saw that I use for demonstrations and I hate it!
If you want to make it Mobil, I would check out Amazon. They have an HTC Mobil base made for the DeWalt saw. It is expensive, but it will keep the base on the ground.