Take one of your front wheels off and just sit down and look at the suspension. After you stare at it a while, you'll find that the easiest way to go coilover would be to add the mounts for dual shocks, much like the rally VX's. Very simple and straightforward, that mod won't have you making all sorts of custom parts and fiddling with the suspension geometry. Just four tabs and brackets per side, some shocks and you're done. Plus you have the upside of being able to switch between the OEM single unit for street and dual coilovers for off-road.