J.D.
My Husband found some of the best bonding was napping together. Once the baby was fed and ready to sleep(or already asleep) they would snuggle up on the couch and sleep.I think this helped my kids get use to his smell. If your husband isn't home often when the baby is awake, make a tape or Cd with his voice singing songs, or reading stories for your son to listen to. And this might sound silly but have your husband sleep with a baby blanket at night, then use that blanket durning the day. The more use to the sounds and smells of your husband the more comfortable your baby will be with him.
The other thing that might work is to put on some headphones while you do your work in the other room. That way you can't hear the baby cry, and it gives Dad a chance to work on his skills, but you're close by to help when HE ask for it. I know I would swoop in too often to save the day because I knew I could stop the baby from crying.
I would also go for short walks around the block or run to the store for short trips. And leave my husband to the Parenting. I had my cell phone and he could call if it got to be too much. I came home a time or two with a baby crying in the playpen, and My Husband on the couch, watching TV, because he had tried everything he knew, and he knew I'd be home soon, and crying wasn't going to hut the baby.
Dad's spend time differently with their kids, so give him some space, to safely figure it out.
He'll find a way to bond with his son.