I assume you are creating work orders using WORKORDER.Create, so to create standard text, call STDTEXT.SetText in a similar manner.
(It's trickier to modify/append to existing text).
Refer to Mincom Object doco (523bod.chm) for explanations, or msqmom.exe (in the executables bin folder with all the other msq exes) if you only need the names of the input/output attributes.