Create my own conditional icon sets

can someone get me started on how I can create my own conditional formatting icon sets and get them into libreoffice calc to extend my options?

For the reference of others there is a Design/Whiteboard page that explains what Conditional Formatting icons are. A related mailing list discussion can be found here. Unfortunately though, these icons are compiled into the source of LO. An example change (related enhancement was fdo#60107) showing the locations and files affected can be found here. It seems they need to be relatively fixed to preserve OOXML compatibility i.e., so that core and extended sets of icons match.

Thanks for the info, the links and the explanation.