Small hands, and bent wrench. I have medium hands and bent wrench and couldn't crack the passeger sensor loose. Easier if you have the SAI removed for sure - then you can do it from above without fail.
I saw them for sale on eBay.de a number of times and with shipping and exhange it worked out to $350.00. I do note, that if you are fine with Redneck repairs though, you can remedy a failing adjustment screw problem (same ones the BMW's have), buy using some PL400 adhesive to permanently adhere the ABS back on to the knurled metal post. I've done this on two rides here and it's as good or better than a commercial strength epoxy. Be careful to not get any of the adhesive to close to the teeth though as you can permanently bind the adjustment screws together. lol