That's very much not true.
You CAN control steppers with max msp through maxuino.
I had exactly your same problems a month ago and now I did some steps in forward, though i am also looking for some help.
Basically if you just connect your easy driver and upload the standard firmata to your arduino you'll be able to control the stepper from maxuino 009 (i've been doing it 5 minutes ago), just by sending PWM signals to the pin you connected to STEP on your easydriver (every "1" message would be a step on the motor) and normal HIGH-LOW signals to the pin connected to DIR.
But the motor doesn't work so smooth, when you get to higher speeds (because of "message" communication) and there seem to be a better way to control it with a stepper firmata, that you can download here: http://www.maxuino.org/downloads
but i'm not able to make it work and i'm struggling with it..
please let me know as soon as you can, if you succeeded somehow
p.s. i mean, how can it not be possible, the web is full with material.
this guy for instance has the same family name of yours: http://www.maxuino.org/archives/121