Here's where u can get a Beta code: http://www.fileplanet.com/promotion/medal-of-honor/signup.aspx
It is very easy and straight forward, just fill out the form and enter the captcha thing and then u will get a code. This will not be the beta code but a redeem code for the Beta key. copy that code and go to http://www.medalofhonor.com/beta to redeem ur Beta key for PS3 or PC (The PC Beta is less buggy then the PS3 so i recommend that but u can do this more then once with diff info if u want to compare). Thats it just download the game from somewhere and have fun getting ur ass kicked if ur used to BFBC2