I hope this helps a little..
some quick info about the process
http://en.wikipedia.org/wiki/Short_selling
"It is important to note that buying shares and then selling them (called "going long") has a very different risk profile from selling short. In the former case, losses are limited (the price can only go down to zero) but gains are unlimited (there is no limit on how high the price can go). In short selling, this is reversed, meaning the possible gains are limited (the stock can only go down to a price of zero), and the seller can lose more than the original value of the share, with no upper limit. For this reason, short selling is usually used as part of a hedge rather than as an investment in its own right.
Many short sellers place a "stop loss order" with their stockbroker after selling a stock short. This is an order to the brokerage to cover the position if the price of the stock should rise to a certain level, in order to limit the loss and avoid the problem of unlimited liability described above. In some cases, if the stock's price skyrockets, the stockbroker may decide to cover the short seller's position immediately and without his consent, in order to guarantee that the short seller will be able to make good on his debt of shares."
I don't have first hand experience with this as I haven't opened my trading account yet.
a snippet of E-Trade's policy toward's short selling
https://us.etrade.com/e/t/welcome/welstatic?gxml=financialcondition.html
10. FINANCIAL INSTRUMENTS WITH OFF-BALANCE-SHEET RISK AND CONCENTRATIONS OF CREDIT RISK
"The Company's customer securities activities are transacted on either a cash or margin basis. In margin transactions, the Company extends credit to the customer, subject to various regulatory and internal margin requirements, collateralized by cash and securities in the customer's account.
As customers write option contracts or sell securities short, the Company may incur losses if the customers do not fulfill their obligations and the collateral in the customers' accounts is not sufficient to fully cover losses which customers may incur from these strategies. To control this risk, the Company monitors margin levels daily, and customers are required to deposit additional collateral, or reduce positions, when necessary.
The Company loans securities temporarily to other brokers in connection with its securities lending activities. The Company receives cash as collateral for the securities loaned. Increases in security prices may cause the market value of the securities loaned to exceed the amount of cash received as collateral. In the event the counterparty to these transactions does not return the loaned securities, the Company may be exposed to the risk of acquiring the securities at prevailing market prices in order to satisfy its customer obligations. The Company controls this risk by requiring credit approvals for counterparties, by monitoring the market value of securities loaned on a daily basis, and by requiring additional cash as collateral or returning collateral when necessary.
The Company borrows securities temporarily from other brokers in connection with its securities borrowing activities. The Company deposits cash as collateral for the securities borrowed. Decreases in security prices may cause the market value of the securities borrowed to fall below the amount of cash deposited as collateral. In the event the counterparty to these transactions does not return collateral, the Company may be exposed to the risk of selling the securities at prevailing market prices. The Company controls this risk by requiring credit approvals for counterparties, by monitoring the collateral values on a daily basis, and by depositing additional collateral with counterparties or receiving cash when deemed necessary."
E-Trade as well as other trading platforms take certain measures to ensure that a short-selling strategy does not adversely affect the individual or the company.