"Slide" regen is normally one of several names for throttle-controlled regen that engages whenever you move the throttle position to less than the present acceleration setting. I don't know which one the sabvoton uses, but there are various versions of it, some that are variable with greater regen the farther you pull the throttle down from the drive setting it was just at, or even the *faster* you do it, some that are a fixed amount as if you were pulling a switch-style ebrake lever, etc.
If the controller has a separate analog input brake control port, then you can use simple variable regen via a separate throttle, or a cable-operated throttle unit pulled by a brake lever, etc., and setup the braking parameters (if any) in the controller software to suit your needs.