is that the exact tool called for in the FSM? it looks like it should work.. but the bolt is going to be on there pretty tight... so you might want a length of pipe to place over the handle of that tool so you can get more mechanical advantage.

might not hurt to replace the spark plug tube gaskets too. If you haven't done the job before, have fun with the AC pump thing (on the drivers side). It's held to its bracket by 4 12mm bolts (one at each corner), then the bracket itself needs to come off. 5, 14mm bolts if I remember correctly.

Removing the radiator will be a big help to getting you more room. I just did my timing belt & water pump... but my replacement water pump wasn't EXACTLY the same size as my original. So it took a little filing to make sure that everything was in spec before the accessory mount would line up properly.