SKILL code to replace various IO Pads based on the center coordinates of MKR;wb layer on each pad

Hello,

 I have an IO pad ring in which various IO pads are placed from an older library. Now I have to replace all IO pads with a New IO library where all new IO pads have reduced dimensions.

I have to place the new IO pads in such a way that the centre of MKR;wb layer remains same as in the older pads because this centre has to be used for probing purposes. 

 I have a SKILL code using which I can place the instance at X-Y coordinates and rotation defined in a separate text file, but how can I get the center coordinates of MKR;wb layer present in each pad into a separate file?

Please help.