yes, this is possible.
First you will need to create the user levels, see the "User Level Authentication" tutorial on the security assist support page:
The basic idea, is that when the user logs in, a session is created that contains their user level.
in the recipe, the session is named userLevel, and it gets set to 1, 2 or three.
to assign the discount is exactly the same as the coupon code recipe, just use the userLevel session variable, and change the value being compared to be the same as the userlevel should apply to.