Slate FSlateDrawElement::MakeCustom and FSlateDrawElement::MakeCustomVerts.

Does anyone have ANY information on how to use these two functions?
Im able to create an ICustomSlateElement for MakeCustom but have no clue how to work with the RHI Commands.
With MakeCustomVerts, i have a bit of an idea how to work with it but having trouble with the ISlateUpdatableInstanceBuffer.
Tried using FSlateUpdatableInstanceBuffer for it but it errors out with unresolved external symbol with it even though i added “SlateRHIRenderer” to the build.cs.

Help would be appreciated.