It is not hard, just take your time, layout your plan, read and study the schematic real good and have them handy.
Getting stuff up the backbone, can be a PITA, but if you take your time and use like a electrical fish tool or something homemade (old style speedometer cable as example) will make it easier. Try to stagger the connectors coming out so not to bunch them all up at the same exit point in the backbone.
You will see a few multi strand cable that are for the grounds. I recommend combining them together with one good connector and proper stud and then bring those to a good ground post installed on the box or somewhere close, than run a seperate ground from batter to the ground post.
Make sure you do run the starter to the battery if possible as well as the one that power the PDM.
On the positive side connectors, pay close attention to which one go to battery post and which one are on the load side of the fuse. If you still have a circuit breaker and not the fuse, recommend to change to the 40 amp fuse.
Take your time to route the wires, avoid tight bends or area where it may chaff later. Would not hurt to have some wire loom to protect like you can buy at parts stores or electrical supply.
At the connectors, install dielectric grease to prevent corosion and water intrusion. I did slip a section of heat shrink over the wire/s prior to connecting, then after it was all test, heated them up to give extra protection form the elements.
Oay attention to the routing and the ones going to the VR, recommend cleaing the wire from any road grim-oil that may have accumulated while you are down there. Also double check the ground for the VR or install an additional one.
Take your time and read the instructions carefully, keep the schematic handy and use for reference and you should have little issue.
When you got everything good and install, then go grab your favorite cold beverage, go back and tiddy up the install and wire routing and you should be good to go.
If you have issue with getting the cover back on, do not get pissed, checked where they may be binding and address by rerouting out of the way while still making sure they are secured and not going to chaff or rub and create problems later.
Keep the document handy for future reference.
Good luck
Oh and the legal disclaimer:
******All install and associated information by you or others does not hold the author, me, liable for any none working componets, faults or equipment failure, busted knuckles, cursing, excessive drinking, marital disputes, thrown wrenches, getting stomp by a Vespa in a drag race, evil eye from your HD friends, failure to get laid, ED, blurr visions etc. Upon success (including if failure occurs later), any enjoyment and thrills of open roads will require at least one drink somewhere for me of the Irish Whiskey variety, even if in proxy (since I may not be there). I am not responsible for any burden that may result from the increase of good looking ladies enjoy your Big Dog, however pcitures of such are always recommended to be sent to the forumn to see if the standards are being met. If increase thrill of the open road or increase of loose good looking ladies result in Erection lasting more than 4 hours, take advantage of it, let your buddies know about it and then try cold water and maybe a visit to the doctor.*******
Safe riding and have fun.