I'm not an expert at this or anything but i've see condoms that say extended pleasure and climax control and such. I don't know how they work or anything but I assume they make him hold out longer. I do know the more you have sex, usually the guy beings to be able to control and hold his load longer purposely. Also usually it takes him longer to come the more you do it. Try the condoms if he's alreay been sexually active for a long time.
I gave this option in that other post that hotasfrick was talking about.. But what I do with my boyfriend sometimes, is when im giving him a hand job or something.. I go until hes about cum, then I stop... Wait a couple seconds until hes calmed down, and go again.. I repeat this maybe 3-4 times...He gets mad at me for doing this, but I don't tell him why im doing it, and plus eventually I will finish, and everything will be fine again.. Haha.. By doing this occasionally, eventually he might get better at controlling himself, and being able to hold out even longer.