In a large bowl mix barbecue sauce, teriyaki sauce, beer, garlic, ginger, onion, black pepper, and salt. Place the roast into the marinade, cover and refrigerate for six hours turning often.
2.
Preheat an outdoor barbecue for indirect heat. Remove the roast from the marinade and pour the marinade into a saucepan. Bring to a boil and cook for 5 minutes. Set aside for use as a basting sauce.
3.
Thread the roast onto a barbecue rotisserie spit above indirect heat. Cook the roast for two hours. Baste often during the last hour with reserved marinade.