My preferences for drawing with fixed coordinates in PCB:
(1) If possible, just set the grid spacing to match requirements and use that.
(2) Otherwise, use Edit > Jump > Jump New Location (hotkey J L) and type in coordinates.
(3) Last resort, for more complex shapes, use some MCAD software to create a DXF and import that to altium. I use SolidEdge 2D (free with registration)
But just realised you are in schematic editor. Jump still applies. But, hmmm, not sure what you are trying to achieve.