The MTB girl in my heart lives on and she wants to tell you, yes you can! Those short little squirts are tricky. Berms and the like are an art. I still try to ride like an MTB girl on my road bike, and some of it pays off. I was the queen of climbs with the folks I rode with and the trick to climbing for me was to quite literally put the nose of the saddle up my rear and as others said, boobs to the tube. Positioning yourself on the nose of the saddle gives you better muscle use without losing grip in the rear.
Keeping your arms low as mentioned and when you get to the crest shove your bike forward and push HARD! Then, get your weight back as you roll over. There are certain folks on this board who can tell you about an incident involving me, a berm, and improper weight distribution that ended ugly. I blame her for inviting totally hot racer boys along on the ride, but that's another story.
Climbing in mountain biking was so much more fun for me than it was on the road because it was usually a shorter! I think if you have a spot that is giving you fits keep riding it. Do it over an over until you get it. Even though other situations may be different it's still practice and will give you confidence.
"True, but if you throw your panties into the middle of the peloton, someone's likely to get hurt."