The Dolyaks, that are carrying the supply's are affected, by speed buffs.
If you keep spamming speed buffs on them they will reach there destination more quickly, and in turn give your quicker exp and rewards.
Warriors can use Banners, the horn speed buff, Guardians speed buffs work, and most likely other classes speed buffs will work as well.
http://guildwars.incgamers.com/wp-co...yak-Escort.jpg