I am trying to mate a non-circular elipse gear set. Each gear is an elipse, with the axis of rotation either in the center of the gear or at one of the elipse focii. This is a valid gear type. When I bring up Solidworks mating, I cannot use tangent or gear mating types. I have tried to mate solids, I have also tried to make lines. Any ideas?

Also, if I have two identical circular gears with the axis of rotation offset from the center, when I use gear mating the speed variation that should occur does not. The two gears rotate about each other is if they were regular gears (which makes them interfer during some parts of the gear path). Using tangent works for this type of gear set, except at the toggle points of the gear pair.