How to freely and manually move a point on a non-orthogonal surface

Hi, I’m just starting out on Grasshopper, and have been introduced to moving attractor points with the MD Slider to make Lines on a Square Grid (for example) shorter to longer depending on the distance from the moving attractor point.

I am now trying to do the same with a point on a sphere instead of a Square Grid, but I cannot find a way to manually move the point like you can on the MD Slider on a flat surface.

Even if there is a roundabout way of manually moving a point along a multi-dimensional curve (say a point on a circle of same radius as the sphere), that will suffice.

Thank you for any help!

Plug the sphere into Evaluate Surface and reparameterize it. Plug the MD slider into the uv input. You should be able to freely navigate.

Thank you so much!