Here is how i installed a alloy swing from a X1 arm on my S1. I used the free S1 manual (in download section) and the recall/service bulletins.
I paid £150 for complete swing arm (delivered) including adjusters, rear engine mount, rear brake and axle.
The same alloy swing arm is used in alot of models. The main reason i swapped is the alloy one looks loads better and other people notice the difference in handling.
Parts you will need:
Alloy swing arm
Longer rear brake pipe.
Other new parts i used
Swing arm bearings
rear brake pads
First jack it up and off with the saddle
Off with plastics, petrol tank, oil tank and hugger
Off with exhaust
Rear wheel etc off and rear brake cable tied out of the way
Next i loosened the isolator bolt with allen key and used a ratch strap to lift the rear of the bike off the ground (close to where the oil tank top mounting bolts are and a beam in the roof sorry no pic). This let me disconnect the suspension and then use trolley jack to support the engine.
Once the engine is securly strapped to trolley jack i removed the engine supports. One on top of engine and one on to rear engine mount.
With isolator bolts out i separated the frame and engine (the front mount is still connected so be careful). Here is the swing arm off (just before i called it a day)
Now assemble your swing arm according to manual. I polished mine by hand not recommended for sanity or finger tips.
I had to grind a mounting off the rear peg supports shown in pic (think the mounting is for oil tank drain).
You can also see the new isolator trial fit.
I also had to shorten the pin close to the foot pegs that locates the isolators (service bulletin B-016B). Important bit now (follow the bulletin) installing the bearings, new seals, belt and isolators. I didnt have the rear isolator replacement tool so this is what i done (yes it is agricultural but it worked):
I removed the foot rest and put m8 stud bar in to spread the frame (notice the marks i will have to polish out).
I had to cut this belt guard down as the new isolator made the fit snug.
Now just refit the rest of the bike together (sounds that easy!) Here is mine with out the plastics which are getting sprayed.
This is a very rough guide and i hope someone with more knowlodge and experience than me will correct me and add to the guide