This is how I do it in P4, P6 is probably the same, but I'm not sure. Make the last frame a key frame. In the animation pallet select (draw a white box around) the last frame. With the cursor in the box hold down left mouse button and drag it to the left (the selection box should turn blue) and relasese the button when it is over the first frame. The result should be that the last frame is now in frame #1 position. Now select everything except freme #1 and hit the delete key.