Well specifying a filter file in a specific location is still just as indirect, and its not clear what problem being able to specify the filter by some alternate path would solve. In any case, the filter system is what is provided to search for anything other than item "names", and you cannot reference a filter file location by path (really no need for that - IMHO).
For now, if you really only want to find all FILES under the current path - you might consider the command: 'Set FLATVIEW=toggle,mixednofolders'
This enables flatview to show all files in the current directory tree... So maybe do a 'Go C:\MyWorks' command before the flatview command and see if it achieves what you want - albeit without the Find command.
You could also run these commanda manually, then save the resulting Opus lister as a custom layout that you could load up in a variety of ways.
No - otherwise I'd have mentioned it :-). And yes, if you want the results in a File Collection you need to use the Find command like you're doing, and it sounds like you have other desires for search criteria than just the 'Files Only' use case you mentioned in the original post, so I can see why the alternative suggestion of using flatview doesn't really fit your request.
If you want the ability to control advanced find criteria directly on the command line - it would be a feature request for GPSoft to consider implementing in the product.