The Key Ops tool is the one you want for what you want to do. You need to select everything in the scene before activating it, then when the window pops up hit the Auto button in the mapping section. This sets the source and target nodes to the same. Then in the top panel you simply set the operation type to Move, and on the righthand side input the frame range and the target frame you want the new range to start at. Note that this will overwrite any existing keys in the target frame range, so make sure it is empty. Also make sure you adjust the new frame range in the OdysseyBase's animation list, or they won't be exported.
Edit: I just realised you meant adjust the position value, not the physical position of the keys on the timeline. Whoops.
Depending on how complex the animation is, it might be easier to just edit the ASCII. Can you provide more specific info?