yes, two ways...
1. If you don't want to buy any extra plugins then figure out the exact movement desired in the shake and create a motion path with those points (be sure to zoom in a little first to avoid picture drop out on the edges). then after the "shake path" is created add a slight motion blur, or ghosting effect to it. If you're doing this to a clip which is continuous (A.K.A the bomb falls, rumbles the ground and the plane flies off into the sunset all in one) just razor the area you want to shake and add the effects to that "sub-clip". Of course this become horribly easy in Pro due to the keyframing options available.
2. there is a plugin out there for AE that, I believe, works in P6.5. it's called "Quake". it comes with a package of other randomizing effects. i don't really remember the company name, but you should be able to google it up. If you have access to AE try playing with the sound sync effects. Some great rumbling shots can be worked out to match footage that way.
hope this helped.