No conflict: sounds very good indeed - You must be very far already.
If they start to work - they will work.
Look into console2 (option: all messages) when/after You test Your new History.
Console2 will normally inform You about faults and location of faults (e. g. missing file). Error messages will guide You also to remaining issues.
No error message usually means that You have won that You are finished.
Though i am not sure whether it contains all You need ( or will still help You ) but I uploaded old history.jar from: 0.8.2+ ( 1.8 based ) from lontronics to
http://rapidshare.de/files/31057196/history.jar.html
for newer ones You would have to check with Fred or Hao.
I always just look into the XUL files to find which they refer to
(=which are needed) - just like i do with html links.
<!DOCTYPE dialog SYSTEM "chrome://communicator/locale/history/findHistory.dtd">
wants to import a language file from ... but i assume You know.
I just check all files - the locations can be changed/edited - e. g. relocated
to history.jar -
I best like to follow examples/paradigms.
You can possibly use/look into mtypes.jar as example.
The mtypes extension was originally inside comm/content/communicator/pref/
I wish You all success!!!