Customizing the manual activity ui

[DON_SHOOT_ME]

Couple of questions -

1. Can I have a separate external web application* cater to the ui of a manual activity?
2. Can I send back data to the BPM activity from the external web app*?

if yes can you please point me to some place where I can avail some samples to exactly know the procedure, otherwise if some one can just detail it out, that would work too.

My requirement is I have to reuse an existing web app which uses spring and flex with the process flow I have in nova bonita(v 4.1)

Regards
Chandan.