Based on the documentation for yaps which is part of abcmidi, there is an alternative way that make work for some software. You can add octave+2 or octave-1 to the key/clef (K:) line or separately on an I: line.
X:1 K:C clef=bass octave=-2 ABcd
X:1
K:C clef=bass octave=-2
ABcd
Doesn't work here, apparently, but may be needed for certain software.