Yes. You can build your own enhanced 3270 interface panels. It's actually fairly easy once you've done it once or twice and get the hang of it.
There are a few tricks of the trade to get it done. The first thing you will want to get your hands on is the "Enhanced 3270 Interface Guide" (SC22-5426-00). This manual contains a lot of the information you need to build and customize your own panels. Here's a link to the manual:
The interface guide documents all the keywords, and shows you many examples of how the panels are coded.
The nice thing is that the panels are just members in a PDS. When you create a new panel, or modify a product provided panel, put the new or updated panel in the -hilev-.UKANWENU library. Don't modify the -hilev-.RKANWENU members directly. Make a copy and put them in -hilev-.UKANWENU.
Testing a new panel is easy. Just enter =panelname (keeping in mind these are PDS members) on the command line and hit enter and your new panel should come up.
I'm working on some new panel ideas. And I will be blogging on my results.