Yes, of *course* you can connect to the internet from (text-mode) run level 3.
It just means that you won't be able to do it with the GUI kpp tool you're accustomed to.
All you need to do is find a command-line tool or daemon that does "dial-up networking" for you.
For example:
http://www.linuxheadquarters.com/how...fg_modem.shtml