I just tried a fresh download of hplip on tc-5.x (tc-4.x does not boot on my hardware).
After setting a root password, starting the cups daemon from the cpanel/services gui and using opera to go to localhost:631, clicking on add printer popped up a dialogue box for the root password and then automagically found my network attached printer as per the screenshot attached.
@Curaga - fifth does not pop up a root password dialogue box, but instead gives the error "Unauthorized
Enter your username and password or the root username and password to access this page. If you are using Kerberos authentication, make sure you have a valid Kerberos ticket."
Even though fifth does apparently upload a screenshot, it gives the error message "
http://forum.tinycorelinux.net/index.php?action=post2;start=11;board=14: error 65, Send failed since rewinding of the data stream failed"