I'd say "some assembly required" for RH-based distros.
The weewx-multi script that comes under util/init.d in the .tgz file is Debian-specific and wouldn't work on a RH-based system. That said, if you diffed the weewx.debian and weewx-multi scripts there, you would see the additions made to support running multiple instances. You'd need to do similar modifications to do a "weewx-multi.redhat" (so to speak) similarly modified init script.
Definitely doable but you'd have to do the doing part. I'm sure Tom+Matthew would love a pull request with a working init file for RH that supports multi.