'Drag' Scrolling in 3D

If I understand what you want, you could use camerapick on the terrain or on an invisible plane, and do something like this...
;keep track of mouse position relative to visable grid function
Function track_mouse(marker,camera)
marker_X#=Int(PickedX#())+.5
marker_Z#=Int(PickedZ#())+.5
marker_Y#=Int(PickedY#())+.5
CameraPick(camera,MouseX(),MouseY())
End Function
parent and point the camera at a point that follows a marker position found with this function.