Unless you have an actual Miller product, you cannot have mid-lift @ 90° etc. geometry on both rocker levers. If you achieve this on the long (valve-side) lever, the short (pushrod-side) lever will have asymmetrical motion B & A 90°, which will reduce maximum lift slightly. The highest lift is some compromise on both sides, and YMMV.
A rocker set at mid-lift will have this scrub pattern:
The scrub path begins at 0% lift with the valve closed and the roller closest to the rocker shaft, and to the stem tip's near edge (not the center).
As the valve opens, the roller walks away from the rocker shaft toward the stem center.
Its path is centered on the stem tip at 25% lift (but this may not be the tip's actual center).
It reaches its farthest point away from the rocker shaft at 50% lift.
As the valve closes, the roller walks back, reaching its own center again at 75% lift, and the same closest point to the shaft at full lift.

The width of the scrub path should be very small, but it cannot be shortened more than it's actual length vs. lift permits - which is determined by the triangle formed by the lever and lift.

I wrote an .xls program that generates ideal scrub in inches and degrees of sweep from known rocker dimensions - e-mail for a copy.