Customizing Datum thru Grid shift files

Hi,

I am in the process of customizing the new datum and Ellipsoid based on our company standards, the method is Grid shift files Nadcon format which is .las and .los files. Can any one guide me in OpenCities Map how to write or in what way the software will accept while defining in Edit Datum Properties. Please see the attached snapshot for more clarification.

Regards

Ilyas