Where can I get [longer/replacement] wheel studs for my [DSM]?

Using wheel spacers usually requires using longer wheel studs. ARP makes some longer wheel studs available through vendors. 
ARP Extended-Length Wheel Studs: DSM

Replacing the stud is fairly easy;

1. Hammer out the old wheel studs
2. Buy a good amount of thick washers fit the stud. (5-8 should do the trick)
3. Put the new stud through and stack washers on threaded end.
4. Grab an air hammer and with your new lug nut (should be open ended) tighten it down as much as you can with air hammer to pull the stud through.

You may have to heat the hub a little to get the new studs to seat. If you have ABS, be mindeful of the sensor.