This is a link to the cam bearing tool I have. The tool is about $150, most shops charge around $100 to tank the block and install bearings, so it really isn't cost efficient if you only use it once.
Some of the larger tool rental places may have one.
http://www.northernautoparts.com/ProductModelDetail.cfm?ProductModelId=1974
The Chevy specific one is about $70, but it won't work for AMCs.
You need to be careful to align the oil hole with the passage in the block. The 4 rear bearings are installed from the front and can be installed with the engine on a stand. The front bearing is installed from the rear, so the engine has to be off most stands.
Bob
tufcj