No sauce, huh??? That'll make things tricky...
I'd try tire warmers if you can't use sauce. I'd also soften my springs and shock oil to get the car to roll more, which should increase grip. Use HPI Yellow 24mm inserts if you can find them, otherwise use HPI 24mm red inserts for those tires. I've used them before with X-Patterns, and they work pretty well.
Are you allowed to clean the tires using Simple Green? It's not quite sauce, but helps with traction.
