Yeah, I put a Harley tach on my 2000 FatBoy. It should be the same procedure for all softails. The tach comes with pretty good instructions and to be honest was very simple to install.
My only caution is on the recommended ground in the wiring harness. The ground in mine was about 10k ohms to ground...not good. I was getting symptoms like the tach was bad, everything would work until the ground was connected and then it was lights out! I recommend attaching the ground wire to a bolt that connects directly to the frame.