If you are using a thermostat, where the probe is connected directly to the heating surface of your UTH, then you will have no problem using paper as your substrate. This is assuming that you are installing your UTH under your snakes tank and not in the tank. (I only say this because you did not specify your intent)

I believe, as do most all others on this site, that any type of UTH requires the use of a thermostat to regulate the amout of heat that your snake is receiving. UTH's typically get to hot to use unregulated.

Hope this helps.

John