I'm not completely certain I understand what you're asking, but if I am following you it seems like you want to have the user make a selection, and then take this selection and enter its value into a form field. Is that correct? If so, then no, that is not something that can be done in Catalyst. You could create the form and the object to be selected, but you would then need to take the project into Flash Builder and add ActionScript to populate the form with the selected value.
That is what I needed to know. Looking to purchase everything that I need to create the website. Making an action script sounds like the way to go. Thanks for your help.
Here is some resources to help you along:
You can transfer projects into Flash Builder to add functionality like this. Be aware that with Flash Catalyst CS5 and Flash Builder 4, this is a one-way trip. Here is a tutorial by Tanya Heins that explains how: