One physical light switch to control a separate smart switch?

None of the official SmartThings features expose the parameters for a Z wave device. You have to do it through a device type handler.

Fortunately recently one community member has created an all purpose Z wave device type handler which just lets you get to the parameters of any Z wave device. Then after you set them the way you want to, reassign the device to the regular DTH you were using before and the parameters will stay set. :sunglasses: