My friend, Mr. Maverick is right again on this one. Rarely will you see leverage on leverage like the OP is asking for. Not being critical, but the comment about losing his money and then relying on the firm to cover additional losses, sort of says it all.
Nothing against the OP for asking. But, what I generally ask people with similar questions is something like this: Hey, I have a track record playing blackjack, easily verifiable. I would like you to back me against any losses, or any big losses anyway. How about it?
Look, I've been barred from blackjack, and I am pretty good. But anyone that would want to get into that relationship...well, you get the idea.
And, on the another point. If you're that good, why give away most of your profits? Simply use the leverage available to build up an account. If you're sure of yourself, whether it's $10k, $50k, or $100k, you can certainly build it up. Then you can start backing people to make even more money.
I hope that makes some sense? Mav? HitnRun?