Finding Precession

I have a project I''m working on to try and get myself into the physics part of physics engine programming. Pretty much, I want to be able to figure out a final force based on the very basic forces applied to an object (for now, I''m restricting myself to rectalinear forces and torque as my basic forces). Now, I''ve managed to get a rectalinear system working based on Chris Hecker''s articles, and I understand the theory behind the rotational physics. The specific problem I posed for myself: Have a spinning cylinder (essentially a gyro) on an arm attached to a pole on which it is mounted. The pole is larger in height than the radius of the gyro. Through theory we know that the gyro will precess, but the experiment is set up in such a way that the gyro cannot precess due to restrictions on axis. What ends up happening, from equations in books, is the arm ends up spinning around the pole (which I believe is called precessional frequency). This problem as applied to my goal: I have gravity and a single torque acting on my spinning cylinder. If I run the sim with those conditions, the cylinder will end up spinning while falling down. What I''m wondering is how do I restrict the cylinder from moving downwards, yet still applying gravity to it, in essense forcing precession to occur. Once I figure that out, I don''t think finding the value of preccesion itself is going to be that problematic as soon as I figure out the restricting part. Any ideas? Thanks in advance -Evgeny