/help Command Line
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"C:\Program Files\mIRC\mirc.exe" -sUndernet
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-r<path>
Sets the data path where mIRC saves mirc.ini as well as other files and data. If -r is specified without a path, the path is set to that of the mIRC executable.
You could always do: "C:\Program Files\mIRC\mirc.exe" -r
For now?