You could try here: post about abc to tab and try to PM the guy concerned.

If not I have a way that you can do it but it is more longwinded. From ABC you can convert it to a midi file as I'm sure you know - eg you go to Concertina.net and save a midi file. I'd then import the file into something like Guitar Pro 5 which I happen to have and it would produce something like this - Example of tab.

I would have thought it would be easier just to work it out on the mandolin!

There is also a program called Melody Assistant which I just tried which produced the following directly from ABC. 20 euros for full version but you can download and test it and produce tabs -

  #-------------------------------PLEASE NOTE------------------------------------#
  #This file is the author's own work and represents their interpretation of the #
  #song. You may only use this file for private study, scholarship, or research. #
  #------------------------------------------------------------------------------#
  #     Harmony-Melody Tab export Vers 1.5, September 2000-August 2004           #
  #                   (c) Myriad Software 1994-2005                              #
  #                   http://www.myriad-online.com                               #
  #
  # h  hammer on    | p  pull off       | b  bend string up
  # r  release bend | /  slide up       | \  slide down
  # v  vibrato      | t  right hand tap | x  play 'note' with heavy damping
  # S  slap         | P  pop            | <> harmonic
  #
  #Title         : Galway Girl
  
  #Composer      : Steve Earle
  
  #Export date   : Wednesday, December 24, 2008  0:46:36
  #File          : galway.abc
  #Staff         : 
  #Tempo         : 60
  #Time Division : 1/4
  #Neck          : Mandolin 
  #------------------------------------------------------------------------------#
  
  
  
  
  NOTE : This a Melody Unregistered version, the export is limited to 8 bars.
  
  E |-----|-----------------------|---------------|---------------|--------------|
  A |-----|-----------------------|-------------0-|-2--2--2-4-5-4-|-2--0--0----0-|
  D |-0-2-|-4----2-4-2-0----0--2--|-4--4--4-2-0---|---------------|----------4---|
  G |-----|-----------------------|---------------|---------------|--------------|
  
  |-------------|--------------|
  |-2--2--0-----|--------------|
  |----------4--|-5-4-5--4--0--|
  |-------------|--------------|
  
  #End of file.
  

It seems to have ignored the triplet but I didn't pay too much attention to it