Some setup advice.....?

[CapeDoctor]

ok, guys, it was inevitable that i ask for some setup advice at some point, and i feel now is a good time, as with my current situation, the more i read up and try to adjust the settings, the more i seem to be screwing up the bike's handling.
i also need to know if maybe i am trying to get around a physics issue with a particular bike, which might negate any attempts at a good setup.
so, to the issue at hand - the track - Hockenheim 79.  the bike - SBK GSXR 1000.
my main problem is when approaching the first 'chicane' after the start, when doing around 300km/h +-, i'm on the left side of the track, leaning slightly right to get the correct entry line to the chicane (ok, it's not really a chicane, i guess, but i'm sure you know what i mean)- when i start braking, because i'm leaning slightly, i first use back brakes, and then dab the front brakes repeatedly to slow down enough. the problem is, the back end of the bike seems to want to snake about, left-right, and starts a back-end 'see-saw' motion which becomes completely uncontrollable unless i manage to slow down enough (which is generally slowing down way too much to get anywhere near a decent lap time.
it also displays this behavior if i try using back brakes only.
what settings should i be looking at adjusting to best counter this problem?
i wanted to ask this, just in case there is also some inherent physics issue with this particular bike, as opposed to/in conjunction with my crappy setup know-how.
anyone willing to give me some pointers here?
thanks in advance 

PS: i would try using someone else's setup from online, but due to my connection issues, especially when there are other riders online, it's hard for me to ever get any shared setups.