As a Debian Linux user I found difficult to abandon the Debian packaging system. Therefore, to Install Modeller 9v4-1 I first converted the rpm to deb with alien (flags -k --scripts. Then I installed the deb package with dpkg (flag -i). The command reports that the package is installed but requires a password, indicating which configuration file to edit to set the password.
That way, you avoid possible blurring of the OS by going through an rpm; deb positions every file at the expected place; you have the modeller command on path; you have full command of packaging in case of installations of new version.
If not already posted by other members, it might be useful, though I understand that Debian (curiously) is not popular in USA.
Cheers