I installed 2way remote start/alarm with pager. I disconnected OEM alarm and used existing wiring. Here is diagram where to splice: http://www.peachparts.com/shopforum/showthread.php?threadid=45588&highlight=keyless+entry+easy It's looks very similar to the one I found somewhere online.
As for remote start I found diagram somewhere online. Ran wires to ignition switch and it work no problem.
Installation is not very complicated since you have all wires from doors,hood,trunk,lights to flash.
Good luck

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1999 ML430 Silver 135k ml
Smoked LED taillights, Alpine in-dash DVD player, 12" sub, Pioneer components, 2 amps, 4200k HIDs, ML55 headlights, 20" rims, mirror LED blinkers

SOLD. 1996 E320 145k ml. Burgundy

SOLD but miss it everyday 1992 500sel Black
Chime buzzer mod,Alpine CD/MP3 player with stock amp,Euro headlights,S600 grill,20" rims, BEST CAR EVER!

SOLD. 1990 300E White
187k ml,smoked tails,Euro headlights,17rims,Intake,12" sub in first aid kit,alarm/autostart,buzzer mod