One way to treat this assignment is to model it after a fable. For instance, in the fable of The North Wind and the Sun by Aesop the two elements compete against each other to see which one can make a man take off his coat; the North Wind tries to force the man's coat off while the Sun beats down upon the man with such heat that he quickly removes it. Thus, the moral is that Persuasion is more effective than Force.
With Aesop's work in mind, then, perhaps a fable of sorts could be composed from the competition of the two roads to entice the traveler to select one over the other. Turning to the text of the poem, the writer of this new "fable" can develop her competition from the descriptions in the second stanza:
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
So, the rivalry is between the grassy path, that is not worn, and the other that shows some usage and is equally inviting. Obviously, then each path must attempt to appear different in order to invite the traveler to select it over the other. And, since the poem does not indicate any differences, the writer will need to create some subtle ones such as taking advantage of the sunlight upon it as an invitation, or the beauty of the flora and fauna that reside along it.
To begin with, the writer could have a short conversation between the two paths while they are alone as they wonder who will come along and which one of them the traveler will choose. Then, perhaps, as in the fable of Aesop, they can challenge each other and claim superiority of appeal. They can be labeled the "grassy path" and the "fair path" as the writer develops the challenge between them to see who can claim the traveler who comes along.