Synchronizer Screw Tool
You have to have some sort of angle drive tool to turn the synch screws. The Honda tool shown in the manual lists for around $60. Alternatives: Snap On P/N TM65, $15. One end has a thumb screw and the other has a 4" flexible extension w/ 1/4" connector for a 7mm socket. Skew tool (a 1/4" drive right angle drive tool; look in hardware stores).
Alternative Screw Tool
You can use a hex driver screwdriver ==> hex to 1/4" socket driver bit ==> 3" 1/4" extension ==> 1/4 universal joint ==> 7mm socket This gives about 1 foot of extension from the handle to the socket. Every screw can be adjusted.