Which guards are you trying to mount?
How many engine bolts need to be out at one time to facilitate installation?
Nevermind... try this:
If you have any punches or screwdrivers or similar improv tools, remove the bolt(s) that go thru the whole engine and insert such tool from the nut side, install the guard on the bolt head side of the engine first. When you push the bolt(s) back in, then you can do the other side.