connecting to a WPA-PSKr from command line

[Mark Ryden <markryde gmail com>]

Hello,
-  I have a wireless router which is configured to work with WPA authentication.
- I can easily connect it with NetworkManager after typing the password.

 - I want to connect it from command line.
  - I tried with iwconfig, but I could not. I googled for it, and saw
suggestions to use
wpa supplicant.
My questions is:
  - is usage of wpa supplicant is a MUST when trying to associate to
wireless router which works with WPA authentication?
  - Can somebody recommend some link that worked for him , which
specifies how to connect a WPA authenticated wireless router with wpa
supplicant?

Rgs,
Mark