What year and specific model is your bike?
On my '81 R65 with dual disk front brakes I would have to remove one of the calipers and hang it from a wire so it doesn't strain the brake hose. Then remove the front tire. After that, both brake calipers are accessible and I would just wiggle out the old pads and wiggle in the new ones. If your old ones are worn down a lot, then take off the top of your master cylinder up on the handlebar, and use a turkey baster or syringe to remove most of the brake fluid. Then you can press the new brake pads into the calipers, which will force some fluid up into the master cylinder. You may need some sort of C clamp or other tool to apply enough pressure to do that.
When the the new pads pushed in far enough you can put the tire on, slipping the disks back into the calipers. Replace the caliper you removed.
Suck out the rest of the fluid in the master cylinder, and refill with new fluid. It should be DOT4 brake fluid. If you have not done it in the past couple of years you should bleed out the old fluid down at the calipers and top up the master cylinder with more new fluid. Changing the brake fluid is a sort of regular maintenance procedure on these.
Hope this helps,
I've never done this job on an LS which is what you have for your avatar, but it should be similar.