I doubt it works like this....
But by "tokens triggering replacement"... I mean, you could have a :::3colontrigger for all EXTENDED smileys, extended being, ones that aren't commonly used in normal conversations like

:P

etc etc... no big deal to have 10 or 20 of those common smileys looped over and replaced (which may be how Vb parses smileys by default?)
But maybe you could get away having tons more smileys on the system if you used a trigger that someone wouldn't normally type... like three colons followed by the smiley name.
When people post a new message, you could put a filter in there that would count (and limit) the number of smiley triggers allowed (including your extended 3 colon trigger smileys) -- to prevent people from attacking the board by making a bunch of repetitive :::3colon tokens with random text.
Make sense?