Sarà... ma ho trovato il modo:

http://www.basis.com/onlinedocs/docu...nction_bbj.htm

Se scorrete in basso leggerete questo:
codice:
[...]
Buttons
0 OK
1 OK and Cancel
2 Abort, Retry, and Ignore
3 Yes, No, and Cancel
4 Yes and No
5 Retry and Cancel
7 Custom
[...]
x=msgbox("Accept print job?",7,"Printing is complete","Yes","Reprint","Fax")