Automatic generation of filter text

Hello,
I am trying to make a page where users can add their ISBN data into a content creation page. For the purposes of testing, I have created two fields: one 'Amazon Item' field with the auto-complete widget and one text field that uses the Amazon Filter Module. In my site, when a user creates a new node, they will input a book's ISBN number into the first field; they will not see the other field because I have hidden it using another module. The default string in this hidden field will use the Amazon Filter text format...[amazon asin action]
The action could be anything.
My issue is figuring out how to input the 'asin' portion of the text, automatically, without the user doing it themselves. Does anybody know how to do this? Maybe with tokens? How can I get the system to spit out the data in the 'Amazon Item' field into this specific portion of the text field?

Thank you
-Oscar