'Plugins' act on 'fields' to modify documents. 'Fields' are defined in a document using EscapeE, see Defining fields and tags. Setting up a field to use a plugin is done via the Action page of the 'Field' dialog.

Click to expand/collapse this hiddedn textTo attach a plugin
1.Select Edit... from the 'Fields' menu (ctrl + d) and click the field you wish to edit from the field name list.
or
Right-click on a field on the page and select Edit field...
2.Click the Action tab.
3.Select one of the options from the drop-down Call Plugin list. The list contains the names of the plugin installed on your system.
oTo add the feature to the 'back' of the target page rather than the 'front', tick On the back. This forces duplex printing even on simplex jobs (long-edge binding if portrait and short-edge binding if landscape).
4.Click Configure.
oBC39Reader and QRCodeReader 2D barcode readers need no further configuration.
oThese plugin display an additional configuration dialog – see specific topics for details:
•ocrust
•rocr
•script
5.Click OK to close the Fields dialog.

Once a field has been configured, you may re-open and edit the Configuration dialog from the right-click pop-up menu option Configure field...
There is a button on the EscapeE toolbar which allows Plugins to be enabled or disabled.

Tip:  If a plugin attempts to modify a PDF document that is marked as not editable then the corresponding field is disabled and a warning given.