Did this on my Heritage Springer a few years back, figured if someone needs the wiring info. (they were the same on my softail and 06 and 2001 roadking)
Here are the pics of my install on a 2001 roadking classic.
I used T-tap connectors and shrouded spades for the 3 wires and a regular female connector for the Tach wire. You will also need wire stripper and wire crimping tool. Electrical tape or heat shrink tubing is optional.





STEP 1:
Make sure bike is off and disconnect neg battery terminal.
Remove console and carefully turn it over and look for a pink wire attached to the odometer harness, this is your tach signal wire.(mine was attached via zip tie from the factory)
-
STEP 2:
Lay console over a shop towel or thick piece of cloth to protect it and the bike while you're working on the wires.

TIPS before you go to step 3:
I found it easier to connect the T-taps when I detached/disconnected the Odo/speedo harness and Ignition harness.

When using T-taps, you can use a wire stripper just enough to cut through the plastic covering of the wire (and NOT cut the wire) to expose the wiring. You can use a screw driver to widen the metal piece of the connector a little bit for a better fit.(see pics)

The blue quick connect spades are easy to install with a crimper tool.(most wire strippers has a built in crimper)


STEP 3:

Here's how to connect them: (see pics)

Green wire from tach to Pink wire in console
Red wire from tach to RED/black" ignition ON" switch wire
Black wire (ground) to #10pin black from odometer harness
Blue wire to Orange wire from instument lamp harness.

-

-

-

-


-

Your install may vary, as to where your final location is for your tach. Mine is on the left side of the handlebar, so I route the tach wire from the console, underneath the triple tree and handlebar clamp.(see pics)



STEP 4:
Verify all connections, re-install console and make sure new Tach wiring does not bind
when handlebars are moved left, right. Reconnect the neg battery wire and verify, move your bike outside the garage (LOL) turn ignition ON and start your bike to make sure your New tach is working.

STEP 5:
Smile and admire your work, turn the bike off and run inside before you freeze your $$$ Off!
It was 19 to 22F when I did this, so I was inside my small garage with a portable radiant heater. Sorry for the pics, it was night time by the time I was done. Install should take about 1-2 hours maybe less if you have all the stuff you need and not loose screws like I did- that handlebar /headlamp nacelle clamp is a pita to install and reinstall,lol