Hi Phil,
regarding the R1150 a-arm (commonly known as telelever)
nothing needs to be changed or modified. The R1100R front shock fits as well as the a-arm itself. The R1100R and the R1150R shar exactly the same geometry. However with the a-arm you also need the axle (you can't use the axle of the r1100r a-arm!). By axle I mean the one which connects the a-arm to the engine block. Loosening the screw of the front ball-joint is a pain because this screw is "glued" with high-tension Loctite and you need to heat the fastening to about 200° celsius to be able to unscrew ... So for the front ball joint you need a heat-gun, an Allan key (I think it was 9 mm) and an offset ring wrench (I think it was 22 or 26 mm). A torque wrench is also compulsory for the whole excercise.
What is not possible to re-use is the steering damper as the R1150R a-arm has no mountpoint (as the R1150R has no steering damper at all!). But riding without the steering damper has never ever been a problem and as a matter of fact steering is easier and there are no drawbacks in my opinion. Again as the 1150 and the 1100 share exactly the same geometry and since the 1150 did not have a steering damper I believe BWM also felt is was not necessary any more.
regarding the wheels
The K1200RS (the flying brick and not the new 4-cylinder!) rear wheel (5") fits the r1100r without any modification! Just plug-on! The front wheel is a different story. You need the wheel of the R1150R (not the one off a Rockster!), the ABS ring of the old R1100S, and new disc rotors dia 305 mm (either the rotors of the old R1100S or some aftermarket rotors - I took those available from Lucas) and the speedo drive of the R1150R. You also need to buy the appropriate fasteners from your dealer as this is special grade steel. Don't buy ordinary screws at your local toolshop! The the left disc-rotor fitting on the wheel 3.9 mm need to be milled away. This is because the ABS ring of the old R1100S (cast metal) is thicker than the ABS-ring of the R1150R (metal sheet). Next mount the disc rotors/ABS ring (loctite!) onto the wheel and your front wheel with the speedo drive to your front fork and you're done ... If you have a non-ABS oilhead it is a different story and more difficult ...
Suggest you also get hold of the manual available on
http://www.carlsalter.com/motorcycle-manuals.asp
If you have other questions please don't hesitate to ask or send me a PM.
Kind regards
Oliver