It is possible, I have done it several times. But there are few things to notice. First thing is that you need to mark the position of the compressor wheel relative to the shaft (make a small scratch or something, not with pen, it will be washed out!).
And it will be visible when removing the compressor housing whether there is even point going any further: if the comp wheel has touched the housing, no point going further.
If wheel seems fine, remove the wheel and then you can access the backplate bolts etc. I don't have repair guide for KKK (I have done several Holsets and Schwitzers), but it would be useful so you can check the factory tolerances for rear seal groove wear limits etc.
Here are few links you might find useful:
Repair guide for KKK:
KKK Turbo rebuild instructions - anyone have them? - Rennlist Discussion Forums
Parts diagram:
http://www.vaglinks.com/docs/catalogues/melett.com_kkkcatalog.pdf
And here's some useful information also:
http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/857790-help-rebuilding-stock-k27-turbo.html