I've written a simple little program for popping up dialogs within script files on PocketBook E-Ink devices. You can show messages, get text or numeric input, ask a yes/no question, pop up the directory selector, and even do (clunky) file selection (based on the OpenContents dialog). I've uploaded the binaries and source code to my website:
http://komary.net/sh_ivtool/. An example shell script that uses it can be seen at:
http://komary.net/edit-epub/. This should make it easier to use non-trivial scripts in the Applications tab.