If you apply something like the below on both ends of the ds3. You will need to reverse the access list so it matches correctly depending on if it is a source or a destination.
If you only need to reserve the traffic in a single direction you can not apply it to both sides.
Be aware if you are running a full rate ds3 (non ATM) card in a 2800 you may have issues running QoS and full line speed. Check your processor load after you attempt this to be sure.
class-map special-user
match access group name special-user
IP access extended special-user
permit ip host x.x.x.x any
Policy-map special-user
class special-user
bandwidth 5000
int sx.x.x
service-policy special-user output
