We do this ourselves at Quantopian, and it would work for anyone. The contest winning algos (hi Grant!), for instance, are running under a prop account.
Walking through that in a bit more detail: Quantopian opened a prop account at IB. We funded the "master" account with several hundred thousand dollars. When we get a new winner, we create a new sub-account and fund it with $100,000. We enter the new sub-account credentials into the regular Quantopian/IB login process and deploy the real-money algo. From the master account we could hypothetically disable the login to the sub-account, liquidate positions, etc.
This works because from an API perspective, most IB accounts are indistinguishable. If it has an account that starts with U (or DU for paper), we can probably support it. I can think of two categories of IB accounts we don't support yet. One is the Financial Advisory accounts, also known as "F" accounts. I doubt we will ever add support for those. The other category we don't support yet is U accounts that are linked to certain extra-high-security devices, the Gold/Platinum security devices. We will support those, probably sooner than later. So far we only support the more common IB code card.
And in answer to your last question, yes, it's only one algo per sub-account.
Disclaimer
The material on this website is provided for informational purposes only and does not constitute an offer to sell, a solicitation to buy, or a recommendation or endorsement for any security or strategy, nor does it constitute an offer to provide investment advisory services by Quantopian. In addition, the material offers no opinion with respect to the suitability of any security or specific investment. No information contained herein should be regarded as a suggestion to engage in or refrain from any investment-related course of action as none of Quantopian nor any of its affiliates is undertaking to provide investment advice, act as an adviser to any plan or entity subject to the Employee Retirement Income Security Act of 1974, as amended, individual retirement account or individual retirement annuity, or give advice in a fiduciary capacity with respect to the materials presented herein. If you are an individual retirement or other investor, contact your financial advisor or other fiduciary unrelated to Quantopian about whether any given investment idea, strategy, product or service described herein may be appropriate for your circumstances. All investments involve risk, including loss of principal. Quantopian makes no guarantees as to the accuracy or completeness of the views expressed in the website. The views are subject to change, and may have become unreliable for various reasons, including changes in market conditions or economic circumstances.