You don't need to do much with an SVT to do half-way decent in RallyX... I'd say get some new shocks (just some replacement Ford Racing ones would do quite well), 16" wheels with some cheap mud/snow tires, and remove some weight.
There's no need for serious modifications if you are doing it solely for fun!
2001 Silver ZX3. "Chaos"
Current mods: I/H/E, ported TB, SVT suspension and rear sway bar, yellow fog lights, 03-04 Focus headlights, mud flaps, Hankook Winter iPikes (195/65/R15) through the winter.
Coming soon: 16" wheels/tires.