I need to enter income from a T4A for "disability insurance", but that is not one of the listed categories under T-slips. Where should it be entered?

If you have a T4A slip, then you enter the amounts on the slip into the same boxes on the TurboTax T4A page. There are many boxes on a T4A slip, and some are for disability related amounts. You may need to scroll down to find the ones you need.