As many people have done it, it is really still a work in progress. New features are being added (sidechain filters, etc) and different tweaks are being used by different people. Gyraf perhaps hasn't made a GSSL using every VCA. Which 218x are you using? I can help if you are using a 2181LB. I have it all scribbled on a PCB layout print-out at home. There are some pieces that can be left out around the pair of VCAs, some resistor values that need to be changed around them per THAT specs, I believe I changed those two 47K summing resistors in the middle to 120K, and I stuck a resistor onto one leg of the threshold pot (I'll check when I get home). If I am reading things right, I am getting slightly under the 2:1, 4:1 and 10:1 ratios which is AOK with me, and the threshold is right where I need it (I forget if it is -20/+20 exactly, but similar). Oh yeah, I did the little mod to adjust the output to balanced unity gain, can't remember right now what that entailed.
Do some more research on what people here have done, and DIVE IN! Nothing is permanent.