Thank you, PaulsMT
I was doing it wrong: creating the Winbox item via Dude > Tools menu inside winbox of x86 server.
Now I found the Tools menu in the Dude Windows Client.
I followed your instruction and it worked perfectly.
Now it keeps the parameters:
Type: execute
Name: winbox
Command: C:\Tools\winbox.exe “[Device.FirstAddress]” “[Device.UserName]” “[Device.Password]”
Thanks! 
