What the OP is looking to do is to pool money in order to overcome the PDT min. BUt he does not want his bud to have the ability to trade any portion of his share. (already a recipe for disaster.)
The only way any of this is theorethically possible is to use the Friends and family advisor account set up. But that assumes that IB only takes into account the master account value when determining PDT. And it also assumes that the master account is the sum of two client accounts under it.
Personally I think the OP, pooled with his friend, is still underfunded to trade stocks. His and his friend's failure is all but guaranteed. And so will be the failure of the firendship when things go wrong. And they most probably will initially barring beginner's luck.
His best bet is to learn to trade index futures and exercise money management strategies. With $15k, he has enough to trade a 1or 2 contracts in ES(S&P emini), YM(Dow Mini), or ER2(Russel 2k emini). And he'll be able to withstand a drawdown of $10k and still be in the game with $5k if he chooses.
With stocks, assuming that the F&M adv acc assumptions are correct, once he loses $5k, and the master account falls below $25k, he's out of the game.