Nothing you can do if you can't call or go online, except have someone at home make the ADRs for you. I'd go that route just for ultrapopular reservations (Ohana dinner, Le Cellier, Chef Mickey's), then wait until you get home to book the others. If you want any reservations that require a credit card hold or prepayment (CRT, dinner shows, Akershus, California Grill, Fantasmic Dining Package), pick someone with whom you are comfortable either leaving your credit card number or asking them to put down their credit card number for your hold. If there's nobody you can trust with that, wait until you can make those reservations yourself.