Here`s how I do it, being I don`t have a tool to install it either. First I use a file to deburr the end of the crank snout. Next I used sand paper to sand down any high spots. Then I clean the crank up with carb cleaner, checking all the passages in the process. When the crank is clean I use a piece of steel pipe, not much different than what would be in used in a house or business. With a screw on cap on the end of the pipe, I ease the gear on, lube the surface, then use a 1 hand small sledge hammer to drive it on. In the past I`ve also used a piece of exhaust pipe I had laying around. I`ve seen some guys use a hammer to drive it on, and a broken or cracked gear would be the result.