Microsoft Access has the capability to create and update DSN's, using the DBEngine object. Here is some sample code that creates/updates two DSN's:

Sub RegisterDB

 Dim s As String

 On Error GoTo err_rdb

 '

 s = "Database=AcmeArizona" & vbCr & _

 "OemToAnsi=No" & vbCr & _

 "Server=ACAZ-W2K-SQL1" & vbCr & _

 "Trusted_Connection=Yes"

 DBEngine.RegisterDatabase "SalesAZ", _

 "SQL Server", True, s

 '

 s = "Database=AS400" & vbCr & _

 "OemToAnsi=No" & vbCr & _

 "Server=ACAZ-NTAPP1" & vbCr & _

 "Trusted_Connection=Yes"

 DBEngine.RegisterDatabase "Sales400", _

 "SQL Server", True, s

exit_rdb:

 Exit Sub

 '

err_rdb:

 MsgBox Err.Description, vbCritical, _

 "Error # " & Err.Number

 Resume exit_rdb

 '

End Sub

The arguments for RegisterDatabase are:
name of DSN,
name of ODBC provider,
whether to persist security info,
connection string