Bicycle Mechanics - Respacing a hub

I'm in the Clydesdale category and I'm tired of having problems with my rear wheel. I am looking at tandem wheelsets as I figure that they're designed to carry more weight than I'll ever ask them to. One wheelset I'm looking at in particular is built around Shimano XT HF08 hubs, which is spaced at 145 mm in the back. The website selling them says that the rear hub can be respaced to 135 mm (what my current frame is) without much fuss. However, they won't tell me how and just stated that I should take the rear wheel to a bike shop and pay them to respace the wheels. I'm a DIY type of guy when it comes to bikes and I'd rather do it myself. I have an idea of how to do this, but I figured I'd just run it by some people who know what they're doing before I potentially shoot myself in the foot.

Here's a diagram of the hub: http://img258.imageshack.us/img258/1325/fhhf08ky3.png

I think that I should remove the 6.5 mm left axle spacer (14), the 3.7 mm right axle spacer (7) and swap the 2.3 mm washer on the right (4) and the 1.0 mm washer on the left (13). This should bring the hub spacing down to 134.8 mm spacing. Is this good enough? Should I go out and get a 2.5 mm washer instead of reusing (4)? Is this entire plan harebrained and doomed to failure?

Nope, you have the correct concept. But I would first make sure the spacing on the drive side is correct as far as chainline goes, then I would just fill in on the non-drive side to get it to 135mm. I would just go to a hardware store and get a bunch of washers. Won't be pretty, but it will be functional.

I'm kinda worried that the axle will be too long for the quick release. Will I need to buy another axle or cut it down?

I'm kinda worried that the axle will be too long for the quick release. Will I need to buy another axle or cut it down?

It will be too long and you will have to either cut it down or replace it with a shorter one.

You will have to cut the axle to fit so it doesn't stick out beyond the dropout faces and a 135 mm hub normally uses a 146 mm long axle.

They are easy to cut with a hacksaw or Dremmel cut-off wheel and then file the cut end smooth and flat. Thread on a locknut before cutting as it will "chase" and clean up the cut end when you remove it.