Ouch.
I used Barron's study guide to study for the OAR. I've had a peek at the Accepted study guide, and one of my siblings has an Accepted ASVAB study guide - all three have sufficient gouge for the MCT. If you've never had a physics class in high school or college, that can be challenging.
My Gouge for PBM: For the PBM, I recommend you buy Micrsoft FSX (or any of its variants), and a joystick and throttle. Program the joystick and throttle buttons to cover all of the major functions, and to contain the "ATC interaction buttons." This will familiarize you with the HOTAS concept that the PBM hopes to convey, plus it will force you to press buttons in response to what you hear, also a PBM concept. Practice maintaining a precise airspeed, precise altitude, and precise heading, for all phases of flight. That will familiarize you with monitoring and adjusting several things at once, as well as adjusting the throttle and joystick simultaneously. Through all phases of flight, follow checklists! This will at least help your brain prepare for the emergency procedures portion.
If you're pinched for cash, use the Google Earth flight simulator instead, with a mouse if need be. Again, practice holding precise heading, altitude, and airspeed. YouTube "random ATC chatter," and tell yourself "whenever I hear (specific thing of choice), I will [respond in this way with the aircraft]." The important thing there is that you are responding in a particular way to what you hear.
The OAR is a souped-up ASVAB (not a fan of standardized testing myself), but the ASTB is full of analogies to real-world situations in aviation. In all honesty, the above isn't what I did. But in hindsight, this would be how I would've prepared for it.