the only way to short these ICO's is to not buy them.
shorting anything requires borrowing the asset, usually paying interest (as an incentive to the lender), selling them and later buying them back.
the other option is a betting platform where people just take side bets, but counter party risk is substantial and your short is limited by the trade collateral and vice versa for your counterparty taking the opposite bet.
the other option is a betting platform where people just take side bets, but counter party risk is substantial and your short is limited by the trade collateral and vice versa for your counterparty taking the opposite bet.