I think that's correct on a 5500. You probably need to use the CLI ipkg interface (ipkg install <packagename>). "qpkg" is the GUI package manager. I don't know if the feeds are correctly set in /etc/ipkg.conf or not, but if they're not you'll need to add the correct feed:
src
scrname can be whatever you want, and that may be slightly wrong, but it should work.