There are two sections in the M104 service manual that show 1. how to check if the cams are in the proper position and 2. how to adjust them if they are not in the proper position. I'd be happy to send them to you if you email me.

I'm not sure if you'll be able to adjust the cams w/o taking the front cover off. You definitely need to remove the chain tensioner. Perhaps you can caterpillar the untensioned chain on the sprockets while rotating the camshafts to avoid removing the front cover.