Just finished testing this on the motorbike on Ohara map, should work with other vehicles as well. Here's the step-by-step guide.
1. Follow all the steps in Dave's guid to set up WPE Pro
2. Spawn as Heavy Weapons Unit
3. Fire off a rocket at the vehicle you wish to constantly have repaired.
4. Drive the vehicle to the repair station on the map (they show up as wrenches when you press 'T'
5. Before getting into range of being able to repair, alt-tab to WPE PRo and begin recording packets.
6. Drive into the range of the repair station, and after you see the system message in WarRock that your vehicle is repaired, stop recording packets.
7. Add this packet to your send list. Sending it at a rate of 400ms will work pretty well for tanks. Going faster than that might show abnormal gameplay.