Hi Dan,
If you have 2013 installed with SampleTank, all that you need to do is to unzip the file you download and copy the folder that contains the instruments to ...
C:\Program Files\IK Multimedia\Instruments... no additional registration is necessary.
Next time you start up BIAB and load in SampleTank, all the sounds will then be there. For what it's worth, I've noticed that BIAB now takes about 30 secs to load up rather than 15 secs, but that might be a disk fragmenting thing that I haven't yet checked out. Equally, it could be that there's more information to read in now because of what I've added to SampleTank. At the end of the day, though, 30 seconds is not a big deal for me.
Each of the sale packages are around 1 GB big (some slightly more, some slightly less). In the end, I purchased the following packages. (Since each package is normally $49, I got 5 for the price of 1!)

Hope this helps! Happy New Year

Noel