Not at the moment, no.
Opus always sorts the files according to a criteria (name, size, date, etc.). It doesn't let you move things around, except by changing the attribute(s) which you're sorting by (e.g. renaming a file).
Here's a thread from a couple of months ago where I think this idea was suggested for the first time: [Custom File Sort Order for paperless office)
If it's something you need, drop GPSoft a request so it's in their database.