You do understand that IB enforces the $2.50 rule - so call them up and ask if you can borrow 1 million shares of MMEX - then they will ask if you have a Margin account with $2.50 million in it.
From IB:
Maintenance Margin = $2.50 if Stock Value <= $2.50
"For short positions, the maintenance requirement on stock greater than $5, is $5 per share or 30% of the stock value, whichever is greater. For short positions in stock where the last sale price/share is less than $5, then the maintenance margin requirement is $2.50 per share or 100% of the stock value, whichever is greater."