Putting the boots on the shell first is just simply a way to keep the condition from happening. I am not saying that you can't hit the center of all 4 boots, you can... I just suggest putting them on the shell first because it eliminates the chance of missing one and causing a "clicking noise".
A little more advice , your friend ... The one you described as being a mechanic, but that not being his job.... He may be knowledgable , BUT DO NOT LET HIM GO INTO THE VALVE TRAIN OF THAT ENGINE ... That 2.4 L Quad Four design engine is one of the toughest in the trade to set up. When it was manufactured the engineers got a little carried away. Everything on it was set up too percisely. Meaning you probably can tear it apart and possibly even find the problem but the chances of you ( two guys in a garage working without micrometers, torque wrenches,or any special tools whatsoever) getting the cyl head alone , reassembled properly, then sealed to engine block (perfectly... not to even mention correctly timing the cams to the crankshaft ) , are right next to ZERO. I am a very seasoned veteran in the trade and even I am very reluctant to tear the head off a Quad Four. Even if I did it there'd be a 50-50 chance of it not sealing back up due to simply age and distortion of the machined surfaces. Do not even try.