Yes you can hook to the cable TV input but you will need to turn off the power to your roof OTA antenna and reprogram your TV. I have a small old style folding rod antenna mounted to my ladder which works better than my batwing.
The longer the elements/rods on the antenna the better it will get the channels below 15. If you only want higher channels UHF, not VHF a smaller antenna will work. You can buy inline amps but check the signal to noise ratio...the more rejection the better. I use a RCA AMP1450F with SmartBoost.