Sorry. I didn't really read your post correctly.
1) Open file manager
2) Edit / Configure custom actions
Now to see how to enter the correct syntax
3) Select deb2xzm
4) Click edit button on right
5) Analyze the commands
6) Create a new action for rpm2xzm
The script for this is at: /opt/porteus-scripts/context-menu/convert_rpm
How do i become super user?
Wear your underpants on the outside and put on a cape.