Maybe not what you're looking for, but most(here, not generally speaking) can probably get a no interest for 12-18 month credit card with a 25-50K limit. Send 25K to a related Paypal account as payment for services. This works around the cash advance fee. You pay about 3% to paypal. Send the proceeds to a bank account. Wire to brokerage account. You can then also margin this money further if desired. After 12-18 months worst case do a balance transfer to another 0 interest promo card.
I'm not advocating this either, but if you are looking to leverage your investments with borrowed money...