I just did my timing belt recently on my 3.4. Thanks to all on this forum and the tips it went well.
I also made a special tool to hold the crankshaft pulley (like Singtoe) it was a little different but it worked great.
The idea of wedging a breaker bar against the frame and bumping the engine
IMHO is a last resort ( could be dangerous ) and you better make darn sure the engine will not start while trying it. I have heard it will work But..........
Jamming something in the flywheel teeth is a worst idea.
Back to the original question yes a chain wrench on the pulley might work. Although I did not try it.
Here is a good write up that shows a chain wrench being used.
5vz-fe timing belt
( thank you to a member on this forum for the link to this . Sorry that I can 't remmeber who it was but thank you )
A couple things I learned was
I wanted to replace the tensioner while I was in there and you do not have to
remove the A/C compressor bracket to do so. With a long 1/4" extension a 1/4" swivel and a shallow 12mm socket we were able to get behind the A/C bracket and get the rear bolt out of the tensioner. (thank you to a member on this forum for the tip . Sorry that I can 't remmeber who it was but thank you, it saved alot of time) It took two people to do but with one underneath and one up top to guide the socket on we got it out. Putting it back on and getting the rear bolt in was tricky but was done. I put a 1/2 wrap of electrical tape on the unthreaded portion of the rear bolt and put it in the rear hole of the new tensioner. This held it in there well enough to get it positioned and the socket back on to tighten it up.
The new water pump came with a gasket and I THOROUGHLY cleaned the surface of the engine and did not use any FIPG sealant. I tightened it down carefully going around in a criss cross pattern on the bolts, and it does not leak as of a week now so its likely not going to.
Don't forget the washer behind the tensioning idler pulley. I did at first and when I tightened it, it would not swivel / pivot up freely after the bolt was tight.