Arduino Nano + Motor Shield

Gents, I have a question. I have MotorShield V1.0 connected to Arduino One. Everything works fine.
But I need to control one motor speed (one direction) via MotorShield by Arduino Nano. And I have only one available pin (PWM).
Is it possible to connect MotorShield to Arduino Nano and contorl the speed by one PWM pin?

ll 6 analog input pins are available. They can also be used as digital pins (pins #14 thru 20)
Digital pin 2, and 13 are not used.
Digital pin 11: DC Motor #1 / Stepper #1
Digital pin 3: DC Motor #2 / Stepper #1
Digital pin 5: DC Motor #3 / Stepper #2
Digital pin 6: DC Motor #4 / Stepper #2
These pins are in use only if the DC/Stepper noted is in use
Digital pin 4, 7, 8 and 12 are used to drive the DC/Stepper motors via the latch
These pins are in use if any DC/steppers are used
Digitals pin 9: Servo #1 control
Digital pin 10: Servo #2 control
These pins are used only if that particular servo is in use