The spacing on a Shimano and a Campagnolo 10 speed cassette is *almost* the same but not spot on - Campagnolo change the spacings across the width of the cassette slightly, Shimano's spacings are constant.
You can run a Campagnolo cassette with Shimano, though, it's just that the shift around the middle of the cassette may not be perfect.
The best way to tackle it, if it is something that you want to do on a long-term basis, would be:
1. Do a full rear gear set-up ... so -
Get the rear gear hanger checked for alignment (always worth doing anyway but in this case gives you the best chance of getting the system working well as a bonus)
Disconnect the rear gear cable, check the high limit screw, reconnect the gear cable
Set up the system as if you were doing a normal Shimano set-up.
2.Once you have done that, go to sprocket 5 on the cassette and just fine-tune the indexing in each direction from the middle of the cassette to average out any errors that arise from using the incorrectly spaced cassette.
3. Check on both chainrings.
HTH
Graeme
Velotech Cycling Ltd - Campagnolo main UK SC