You need to use a named parameter and pass it by reference. Something like this.
lnId = 0
lnResult = THIS.oSQL.execute("Execute sp_ww_NewId ?@lnId")
On return lnID will hold the result value. In many instances you'll also generate the result value as part of a cursor in the SP. If that's the case you can just look at the returned cursor as well.
+++ Rick ---