To use ROOT directly from AFS you only have to set the ROOTSYS environment variable to point to one of the following directories:
/afs/cern.ch/sw/lcg/external/root/5.12.00/slc3_ia32_gcc323/root for slc3 gcc3.2.3 /afs/cern.ch/sw/lcg/external/root/5.12.00/slc3_ia32_gcc323_dbg/root for slc3 gcc3.2.3/debug /afs/cern.ch/sw/lcg/external/root/5.12.00/slc3_ia32_gcc344/root for slc3 gcc3.4.4 /afs/cern.ch/sw/lcg/external/root/5.12.00/slc3_amd64_gcc344/root for slc3 amd64 gcc3.4.4 /afs/cern.ch/sw/lcg/external/root/5.12.00/slc4_ia32_gcc345/root for slc4 gcc3.4.5 /afs/cern.ch/sw/lcg/external/root/5.12.00/slc4_amd64_gcc345/root for slc4 amd64 gcc3.4.5 /afs/cern.ch/sw/lcg/external/root/5.12.00/win32_vc71_dbg/root for win32 msvc7.1Previous versions or debug versions are also available. See full list under /afs/cern.ch/sw/root.
After this, set the other environment variables as described in $ROOTSYS/AA_README.