You can do this in generic G (labview)
Read the x and y min and max
calculate the centerposition and move the selected cursor to this posistion.
A problem exists when the cursor is locked.
In that case you should calculate the index position closest to the center of the graph and move the selected cursor to those indexes.
In lv6 this is a job for a control reference.
Be aware only to write those properties that are necessary for moving the selected cursor.
Otherwise a race condition with a user moving the cursor and the program moving the cursor could occur.
greetings from the Netherlands