Is it possible to use Flatiron's resourcefull (ODM) in express.js?
Yes.
You'll want to use express's resource router project, https://github.com/visionmedia/express-resource/. This will require a little bit of setup since you'll need to map each resourceful method call.
I would recommend looking at Flatiron's resource router https://github.com/flatiron/restful, since it requires zero-configuration for working with Resourceful resources.
There's nothing in Resourceful that is specific to any other package; the readme at https://github.com/flatiron/resourceful does a good job of showing how you would use this package in any project (not just Express-based ones).