Why don't you want the deer to dig a pit? If your doing this on your own land, what's it hurt? On the other hand, if you're on state land, be sure to check local laws and regulations.
If you continue to utilize the same mineral site, there will eventually be a pit, even if poured onto a stump. The minerals will leach into the soil, and the deer will dig for them.
The best place to locate a mineral site, is in a transition zone, or travel corridor where multiple trails exist. I also prefer the trophy rocks, and replenish as needed.
The best time to start a mineral site is as early as possible, and keep it maintained at least through summer and fall.