Maybe there is something I don't understand, but for your application with a manual lathe, I don't see the use of a home switch.
The use of the home switch is to have a repeatable position of your G54 when you restart your machine so you don't have to teach the origin of your work piece every morning. As long as the machine is powered up, the CNC doesn't care for your home switch. It will go with your encoder or stepper pulse count.
So if it doesn't disturb you to teach the position of your work piece after every start up, I think you don't need them. But I could be horribly wrong also.