1. When a company goes through bankruptcy, the court examines transactions the company made both before and after filing. Any transaction that the court judges as harmful to the "estate" of the company can be undone. The classic example is assets sold off to a friendly party at a token price, but the transaction doesn't have to be blatantly fraudulent to be voided. By that reasoning, transactions from BP's recent past, like the recent shareholder dividend, can be revisited and may be undone.
2. If you win a judgment against someone who can't afford to pay, you can garnish the person's wages and make them pay you over time. It should be a simple process to attach profits of a company under the same principle.
This is why I don't favor seizing the company. BP has the 5th highest profits in the world. When you seize a company, you only get its net assets, no future profits. When you attach profits, you have hooks into the company for years. The cleanup and recovery will take years, so this is appropriate. Injured parties stand to recover a lot more by garnishing profits over time than selling off assets in a bad economy.