The SAMPLES\SMS\SMSAPI directory contains sample code that adds or deletes applications the same way as SMSADDIN.EXE. ISVs can build this code into their setup application as an alternative to running SMSADDIN.EXE from the setup program.
The sample code is contained in two files: ISVREG.C and ISVREG.H. The code includes routines that add or delete an application, plus functions that support these routines. The input structures for these routines contain all of the strings and values required to register an application. (These strings and values correspond to the input fields in the SMS Add-in Tool Registration window that appears when SMSADDIN.EXE is run interactively.) The code can also register an application in multiple contexts.
For additional information, see the sample files ISVREG.C and ISVREG.H.