Well, it's a matter of getting in touch with one of their regional reps. I'd suggest calling information to get the number for Hasbro corporate. They're located in Pawtucket, RI if you need to know.
They can help you establish an account. However, you have to make, at least as of the last time I'd heard, an initial order of $5,000 or more. All subsequent orders have to be substantial, at least over $1,000 in value.