I have had them in both my Epics. My first boat had a Mercruiser one installed by the dealer. I purchased one and put it on my SX as soon as I bought it. I think they discontinued the one I used. There's pics on here of it. I was able to install it without cutting any wires. It plugs in place of the keyswitch, and you mount a small square module under the dash. It took about 30 minutes. I highly recommend it, very handy option.
One thing I like is that it is hooked to the blower, and automatically runs it when you shut off, and when you are below 1500 rpms.
I'll do a search and see if I can find the one I bought. It was from West Marine but it was on closeout.
Pete