I have a Liberty safe, and went the opposite direction when I purchased it: had them swap the digital lock out and put an old fashioned dial lock in. Two reasons: 1) didn't want to rely on a battery operated device failing, in which case I can't get to my treasures for awhile 2) concern with burglars figuring out the combo based on fingerprints (yeah, I know, its an "out there" idea, but...)
Although I haven't checked recently, I do recall that Liberty sold the digital locks on their website. After watching the installers swap the locks, I'm not sure I would attempt it myself, at least not without some detailed instructions.
"Just doing what I can with what I got" Burt Gummer, Tremors II