I tried to see if you could just pass the info you want from Opus to a vbscript, but it seems Microsoft still hasn't implemented a native OS mechanism to SET extended file properties like the ntfs Keywords and Comments summary fields via script...
There's an old COM object extension you can install called Dsofile that you can download, install, and then utilize in vbscript in order to SET some of those field values though...
If you're interested, it would be pretty trivial to write a script, and then send the file info you want to it from an Opus button/hotkey/contextmenu/whatever to have the script write the data for you...
One thing I'd caution you on though... be wary of apps that save updates made to files as NEW files when hitting save 
... as those copies would probably NOT retain the metadata from the original file... while testing out Dsofile quickly against the very script running the actual code, I found that my editor (UltraEdit) was saving off the original version of my script (as I like it to) and the "updated" version no longer had the comment I was expecting to see in my code output... 
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