1. how is your overall fitness? I improved my climbing significantly by working on cycle specific fitness in the winter: spin classes, trainer w/dvds, whatever
2. with #1 you will be able to push harder in at least gear #2 or #3. My goal is to never use my granny on long sustained climbs, but sometimes you just gotta go there.
Fireroad and sustained easy climbing is different from climbing on technical single track. Also, you can train for hills on hills. Go find a hill somewhere close to you, and ride it a lot. You can't help but improve. I have a 3.5 mile fireroad climb out my back door, and if I do it 2x a week, the gains are significant for me.