I would like to pre-populate a form or pre-select an option on a form (from the form and list module)

Given that the forms are generated dynamically; am i right in thinking that it won't be possible to do this?

further info:
i will have several forms on our website. The form in question could be accessed via 2 different ways:
If a user comes from a particular page - i would like to send a value to one of the form labels (pre selecting one of the options available).

even if the same form accessed via another page is not meant to be pre-populated?

In other words:
ROUTE 1: populate this form label with value x
ROUTE2 : do NOT pre-populate with any value

thanks,
mark.