Hi willy,
PlanetPress doesn't have this as a native feature.
Perhaps you could try to use passthrough commands to enter custom pdf code that would allow you to generate a fillable field. You could create a PressTalk object, use the "passthrough" command, and pass your code in it. You will have to do some research on the syntax, however. But here's a link to something that might help:
http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdfmarkreference.pdfThis is a reference guide for the "pdfmark" features, which is code to incorporate various objects, such as fillable fields, radio buttons, hyperlinks, etc... in a pdf. Perhaps you can use this as a starting point, and go from there.
(NOTE: custom passthrough commands are not officially supported by us, so if it doesn't work, there is nothing we can do)
Regards,
Raphaël Lalonde Lefebvre