Norton equivalent with dependent source
One way to find the Norton (or Thevenin) Eq. is to determine the short circuit current \$i_{SC}\$ and the open circuit voltage \$v_{OS}\$ of your circuit.

I.e. you have to analyze following two variants of your circuit:


With a short between the terminals, find the current that is going through the short and
with the terimals open, find the voltage across the terminals. 


The Norton (or Thevenin) resistance then is \$R_N = R_{Th} = v_{OC} / i_{SC}\$.
The Norton current source value is \$i_N = i_{SC}\$.
(The Thevenin voltage source value would be \$v_{Th} = v_{OC}\$)