Hi David,
ok, you don't need to make it a text field, but what you do need to do is make sure the field is _not_ sent to the server in "real time".
ie turn off auto-validate for the field, make sure it doesn't "reset" any other fields, and has "send new value to server" off.
the problem of "interpreting" the string is in the client-side (javascript) code, not the server side code. But by not sending the value to server, you can bypass the javascript code for now.
Cheers
Bruce