Why not find an existing footprint in the Eagle library, which matches the one in the datasheet?
In the Board screen, set the grid to mm, with a 1mm spacing and make it visible.
Click the 'Add' icon in the Schematic screen, then navigate the library to "pot - TRIM_EU- - TRIM_EU-CA9H". Click OK.
Switch back to the Board screen & count the spacing between the outer pins....should be 5mm on centre. Count the spacing between the outer pins and the wiper pin....should be 2.5mm on centre. Check the hole size....should be 1mm.
Print out the board view on plain paper & try your pot for size.
HTH.