No way to avoid the 10% penalty, sorry. But I'm a little confused - you wrote that you "borrowed your own money" - if you mean this literally, meaning you took a loan against your 401(k) as opposed to taking witjdrawals, then no taxes or penalties are due. I'm guessing you really didn't mean to say that you borrowed from your account, but rather took withdrawals, but please confirm.
As for what to do if you can't afford to pay the taxes and penalties you owe - the IRS is willing to work with you to stretch out your payments. See:
Payment Plans, Installment Agreements