well, that all depends on what type of jamma harness you have. There is the crimp type and there is the solder type. I have never seen crimp stuff on buttons but haven't seen the inside of many cabs either. You are only putting in two buttons and that's only 8 solder spots total. IMO, that shouldn't be too tough...even for someone with no soldering experience. 2 wires per button and 2 ends per wire.... not much to it.
Open up your cab and see what has been used in there. If the Harness is the solder type, you are most likely going to have to solder the 4 wires to it.
Use the tinning method above and you should be fine...
step by step
take the end of you soldering iron and get a small amount of solder on it...then touch the iron's tip to the 26 pin on the harness. The solder should tranfer to the pin after about a second. Then, touch the solder to the 3/16 of an inch stripped end of the wire....then place the soldering iron between the two until the solder covers the end of the wire pretty well. Then, do this to all of the "d" pin on the harness(LOWERCASE "d") ,which will be directly below the 26 pin. Do the same thing with 2 ground pins and the rest of the wires.
Once everything has been tinned, you can set that stuff aside while you find a drill bit that is the size of the screw in portion of the buttons you are going to install. Make sure your hole is not bigger then the piece that will screw onto the button from the bottom or the outer rim or the top of the button, so your button will stay in place on the board. (sorry, not to be insulting, but I like to cover all the angles)... Mount in your buttons and plug the switch part into the bottom of the buttons with the common piece on the outer end of the button. Tin the solder spots on the switch parts of the button, which is what is pictured in one of my above post.
Now you are ready to connect the wires...
Ground goes to the Normally Open pin on the switch and the push 5 wire goes to the Common part of the switch. ...as labeled on the picture above!
Remember, 1st player goes to pin "26" and 2nd to pin "d"
IMO, you should be able to mount the 2 buttons and install them in about 15-20 minutes tops....but take your time
Good luck! and make sure to throw up some pictures when you're done.
ttyl,
ngt