There are no special coding steps for calling the Teradata PT from an XSP. As in all applications currently using Teradata PT, the XSP must include the Teradata PT header files and follow the standard Teradata PT coding conventions described in this programmer guide.
Detailed instructions on how to code an XSP are in the External Stored Procedure section of Teradata Vantage™ - SQL External Routine Programming, B035-1147. For information on obtaining this Teradata publication, see Related Documentation.