When and how to change clutch fluid?
No one really changes it. It's just DOT3 brake fluid. It will last a long time. Even if it absorbs a lot of moisture, the slave cylinder doesn't get hot like a brake caliper so it will never "fade". 
Once you start to open those lines you stand the chance of screwing up the feel and it can be very hard to get the feel back, so most folks don't take the chance.
I think if you really wanted to do it, I would make a power bleeder and do it just like you would the brake master cylinder. You pressurize the reservoir (5-10psi) and then crack open the bleeder valve on the tranny. Theoretically, it should work.
Once you start to open those lines you stand the chance of screwing up the feel and it can be very hard to get the feel back, so most folks don't take the chance.
I think if you really wanted to do it, I would make a power bleeder and do it just like you would the brake master cylinder. You pressurize the reservoir (5-10psi) and then crack open the bleeder valve on the tranny. Theoretically, it should work.
