Do you really believe the only way to implement ligatures is with a virtual machine? Dumb and dirty psuedocode written in 5 seconds of thinking about it but come on, this is not that complicated.
for each character in text
characterToPrint = Parse(character)
if character is LigatureStartCandidate
characterToPrint = LookAheadForNextLigatureCandidateAndResolve(character)
Print(characterToPrint)
