Effect to control Pan and Tilt

On our ELEMENT 2 I've created my own fixture profile for a U'KIng MH (10 chan). If I put different values into the pan and tilt, and save in a cue and the change those values and save in the next cue things look like they are working well. I can see the P&T moving from old to new positions. Now I would like make an effect that will repeatedly swing the lamp around between the two P&T positions. I suspect I should be looking at creating an absolute effect. Right/Wrong? And not sure how I get both fields changing at same time as I could in step based effects. IE Pan swinging back and forward with tilt going up and down.