if you're really cheap, you could experiment with grinding a deeper notch in the collar, or finding a lower profile collar off another shock, but that's a half-ass fix. check out that post on the R1 shock swap, you may get some ideas...
I'm thinking that would change the pre-load, but it would still have the same spring-rate. Hmmm. Interesting thought.
I've read the R1 posts and other shock posts on the forum. So far they seem to have resulted in expensive and/or inconclusive results.
I called a couple of suspension places - they suggested that "guessing" at a softer spring rate is not likely to produce a satisfactory result.
Since I am too far away to drop my V off at their place for them to tinker on, they suggested that I send them my spring, (along with the swingarm, pivot, shock mount dimensions, my weight, bike weight, photo of bike, and riding style) and they may be able to work up what I need for a spring.
Since we have at least 4 months of winter here in Wisconsin, I might pull off the spring and mail it out.