LV} I connect to a BBS that is near to my house at
  } 33.6.  I can only download a quick packet from
  } him when I connect at 28.8 or less.  The init to
  } disable 33.6 and 31.2 is ATS56.5=1.
That doesn't look right ("S" registers don't usually have fractional
numbers).  But assuming it was, and assuming that the same thing
with "=0" re-enables it, you would set up two dialing prefixes in
COMMO.SET:
  {set _dialpf,ATDT S56.5=0}     Default prefix
  {set dialpf1,ATDT S56.5=1}     Prefix to disable 33.6
All of your entries in the Dialing Directory will be the same except
the ones where you need to disable 33.6.  Those will look like this:
  Some BBS {%dialpf1 555-1234} {pword} ... etc.
                                - Fred -
---
 þ SLMR 2.1a #359 þ                                     
---------------