I've not yet had to replace a cam belt on a Punto 16V.  My wife's 1.8ie HGT
Punto is due for one soon and I intend to do it myself.   I also have the
Fiat and Haynes workshop manuals and note the method and tools required with
interest.

I have been told that even with the cam belt tensioner released there is not
much slack in the belt and removal and replacement is a little tight and
being able to lock everything down makes things easier.  Also remember that
the procedures are written for belt replacment AND engine rebuild.  If a
rebuild then one would need the tools.  For a replacement then due care and
attention is probably Ok.

Some tips I can suggest are:

A) loosen the crank pulley nut/nuts
1) remove the spark plugs!
2) put the engine a TDC or BDC (top dead center / bottom dead center)
3) put in 1st/reverse gear
4) lock the flywheel
5) mark existing belt, pulleys, tensioner etc. with chalk or other maker
6) be extra careful to ensure the two cam shaft pulleys/sprockets are
accuraqtely measured relative to each other
7) use an old cambelt to lock the camshaft pulleys realtive to each other
8) take it slow and easy.

Nick /////