Convincing Companies to Provide Places to Plug In

>Do any of you plug your cars in at a place of business?
Yes
>How does an employee (or customer) get permission to plug in?
Ask. I approached the building maintenance manager.
>Did your company install a special outlet for you to plug into, or do you just use an existing outlet?
Existing. (GFCI since it's mounted in the parking lot on a lamppost)
>Are small businesses easier to convince than large ones?
No idea. Our company employs about 300 people at our location.
>For a larger company, where would you start? Who would you contact first?
Start small. (lower on the org chart) Sometimes they can make these decisions without upper management.
>Does anybody have any experience with this?
I have plugged in when necessary since August.

Make sure you offer to pay for the electricity. They may or may not charge you, but it shows your concern for the company. Also sometimes the small amount of money that electricity costs (compared to the rest of the companies costs) will help them make the decision.
Good Luck.
Chris