Where to find the corrected BLOSUM matrices?
Okay, I emailed Dr. Mark Styczynsk (one of the authors) to ask about a link to the matrix. Here are the links he gave me:

http://web.mit.edu/bamel/blosum/revised_blosum.c

http://web.mit.edu/bamel/blosum/original_blosum.c

http://web.mit.edu/bamel/blosum/RBLOSUM64 (isentropic with BLOSUM62)

http://web.mit.edu/bamel/blosum/RBLOSUM62 (not isentropic, but it's 62)

The first link is to the c code to generate the corrected BLOSUM. According to Mark, just replacing the original c file in the original BLOSUM tarball with the revised c file can generate the corrected matrix for any of the BLOSUMs (30, 50, 92). Haven't yet tried that myself.