I'd start with washing the bushings with high pressure water. (BTW, this is sometimes a body mount issue too). Dirt can get in there and cause the squeaking. A quicker fix, of course, is to spray those bushings with lubricant. If you find the squeak, then spray with high pressure water to see if it's a dirt issue.
The leaf springs are not hard to do if you have the tools to jack up the H3, support the axle, etc. (We supported the axle with a ratchet strap to the frame.) But seeing how you're up north you may be dealing with rust and that makes those bolts a whole lot harder to deal with. Jack the vehicle, support the axle and the vehicle, remove the tire, remove the lower shock mount, remove the u-bolts, remove the bolts on either end of the leaf spring.
Note that the gas tank skid does get in the way of the driver's side bolt, so you may need to remove that. If the skid is dented in, it will need to be pounded out to reinstall.
If you're doing this, you will want to replace the shackle bushings in the body as well. Those bushings do wear out. Best place I've found for them is rockauto.com but you need to search under 2006 H3. For some reason they do not list that part under other years even though they fit all years and makes of the H3.
Make sure you use new u-bolts on the reinstall. They are not intended to be reused.
