Is there a way to add custom delimiters to an existing language?

[KTamas]

A friend of mine and I have created an Ubiquity command for parsing
the Hungarian national railway's timetable (code is here:
http://github.com/gazs/elvira-ubiquity/blob/master/elvira.js). It
takes the following arguments:

- From (station)
- To (station)
- As (student, bike, other reductions)
- At (date)
- Via (station)

Now, the very last argument, 'via' poses an interesting issue. Right
how it's an *instrument* parameter so I can use the keyword 'with' but
I'd really like to use 'via' instead for obvious reasons. Is there any
way to define custom delimiters for an existing language (i.e.
English), and if yes, how?

Thanks
Tamas