First confirm that /usr/bin/diffmerge
	  is present.
	  On Linux, this should have been installed for you.
	
Add the following lines to your .hgrc:
[extensions] hgext.extdiff = [extdiff] cmd.diffmerge = /usr/bin/diffmerge [merge-tools] diffmerge.executable = /usr/bin/diffmerge diffmerge.args = --result=$output $local $base $other diffmerge.binary = False diffmerge.symlinks = False diffmerge.gui = True diffmerge.premerge = True

