Ok, you didn't mention your specific injury but you def should wear a helmet during vaulting excercises. Working on sets of 10: short sprints, high step runs, leg springs (jogging while driving knees in the air), lunges on the grass would be a decent start. Try to increase your speed towards the drills so you can increase heart rate, flexibility and endurance.
You can also work on those vaulting drills without actually jumping to work on your planting, run-through steps and runway speed when you actually start vaulting. If you do any weigh training, maybe bubkas/pullups, situps/crunches/dips, some free weights on arms & legs.
I notice Jan has a nice training log you might want to check out for workouts:
http://www.skyjumpers.com/pages/training.htm. I'm pretty sure others know a few other sites & tips to help you back into form. good luck.
Where do all the old catapoles go....? Ask Jan.