Build other qt libraries with ritual?

[lf-]

I would like to bind to KF5GuiAddons, which is only exposed as a cmake Find module. It looks to me that the infrastructure for qt_ritual_build, e.g. is hardcoded to only work on first party Qt things. As far as I can tell, it's at least very hard to use ritual to build things that are not bundled with Qt, if not entirely not possible. Regardless, I can't find any documentation on how to do it.