You would have to transfer the 401(k) from your former employer to your current employer’s 401(k) plan in order for the new employer to withhold the correct repayment amount from your current paycheck. Realize too, that SHOULD you leave your current employer with an outstanding 401(k) loan, you would be required to repay the loan, or if you could not, the outstanding loan amount would be deemed a distribution, and taxed to you in your current tax bracket, and you would also have to pay an early withdrawal penalty of 10% if you are under age 59 1/2.

HOWEVER be advised that 401(k) loans for purposes-other-than-the-purchase-of-a-new-home, are amortized over a 5 year period, and repayments are deducted directly from your paycheck. I love the fact that the loan will get repaid, automatically from your paycheck, AND that the interest rate you are paying is credited right back into your account.
Depending on the interest rate charged however, this monthly repayment amount could be sizable. For example, a $17,000 loan over 5 years at 5% interest equates to a $320.81 monthly repayment deduction from your paycheck that automatically gets deposited into your 401(k) account. The same $17,000 loan at 4% equates to $313.08 per month. Add the cost of the roof repair atop that credit card loan amount and if you cannot afford the repayment schedule, given that the loan amortization period is a short 5 years, then work backwards to determine how much you can afford as a monthly repayment, and borrow that amount.
Your credit card debt is generally amortized over a much longer period than 5 years, hence the low minimum payment thereon.
If you have established a Home Equity Line of credit–with your house value as collateral–I may suggest that you utilize that line of credit for either the roof repairs OR the repayment of credit card debt, since the amortization of a Home Equity Line is generally 15 or 20 years, resulting in a lower payment. Remember, you can always send in extra principal payments any month as well to reduce the overall interest you are paying. In the case of borrowing from a Home Equity Line, one can generally tax-deduct the interest paid on amounts borrowed up to $100,000, so in this way, you convert the interest you are paying on the credit cards to tax-deductible interest, which is favorable to non-tax-deductible interest.
So, figure our what you can afford to pay each month towards the loan repayment and possibly utilize both of these seemingly available sources–401(k) loan and/or Home Equity Loan.
Good luck Shawn, and write back if you have further questions!