[Al Skierkiewicz]

Toby,
What you are asking leaves me wondering about safety. This is a point where we have to really point you to a mentor that can discuss this with you and watch over what you do. Household current is not something to fool around with as it can kill and set fires if mishandled.
As you can see from the above answers, four CIMs are an overkill for this project as you don't need to raise the TV that quickly. We typically are raising devices on a TV set at much less than one foot per sec and typically the height of the TV (30-40 inches) in about 15 seconds. Any faster and the support hardware and structure take too much of a beating when you stop. The garage door opener motor in the link that Sanddrag has given above looks like a pretty good start. Remember that the motor is designed to lift a balanced garage door so it is likely producing the required lift for you project. It might even have all the needed end limit switches that you should use in your project.