I'm going to disagree with this. With the right gearing you can climb all day and do as many repeats as you want but if you're not riding at or above your threshold it won't do any good.

robbleebob your task is straightforward: you need to improve your 6 min W/kg by about 13%. As mentioned earlier 6x5 min intervals at VO2Max power 3 times a week would be a good start. The 13% gain can come from power increase and/or weight loss, preferably both. If your body fat % is already low then you'll have to work on power only. Do you have a powermeter?