When you have bad credit getting any loans including an installment loan can be a hard thing to do.
However it is possible sometimes to get loans and installment loans with bad credit if you have some type of security such as a car or home etc that you can put up as collateral.
Check out One main Finance as they are good for people who have bad credit and will usually approve a loan for you even when you have bad or poor credit.
You might also check into getting a title loan.
Some other loan companies online offer installment loans for people with bad or poor credit.
You might also need to have someone who has good credit help you in cosigning the loan agreement to get the installment loan if you have bad credit.