One- Your mod is missing which file to edit in step 2 (Admin/Modlist.pl)
Two-I guess you are using som out of date messageindex,pl file because the string it's looking for and modifies is no good (moderator check is missing) and spacing is poor which causes error.
your code searches this:
if ((${$uid.$musername}{'regdate'} && $threadstartdate > $registrationdate) || ${$uid.$musername}{'status'} eq "Administrator"
my messageindex.pl (v 2.1 date 8 nov 2005 rev.1.12) has this;
if ((${$uid.$musername}{'regdate'} && $threadstartdate > $registrationdate) || ${$uid.$musername}{'status'} eq "Administrator" || ${$uid.$musername}{'status'} eq "Global Moderator") {
And I bluntly put that in the mod to see if that did the trick, since your code goes "before" that peace it should not be a problem.
Further, after studiing your mod it ends with a curly bracket which cause a missing curly bracket somewhere els so the error is bound to happen sometime. Somewhere in the line you need an opening bracket or a closing one an because of the error in 130X I guess you're not closing tags somehow?
Anyway I'll send you my messageindex.pl to give you the opportunity to try and find a solution taht should work on the newest CVS-ed version I use. ( 2 weeks old now)