Yes, just like the title says.
Well, actually it's not really EASY easy (crowd disperses). The concepts may take a while to fully soak in but once you have the trick you will be able to convert banjo to guitar relatively quickly and painlessly.
There are a number of tunings we could use to get the guitar prepped for banjo duty (open G would seem the obvious choice) but for this particular method we will use open D tuning. Open D tuning involves tuning your guitar from low to high D A D F# A D.
Once you have your guitar in D tuning you are ready to begin.
The idea is this; think of your guitar's 5th, 4th, 3rd and 2nd strings (A D F# A) as being relative to the 4th, 3rd, 2nd and 1st strings (D G B D) on your banjo (in standard G tuning). Then think of the 1st string of your guitar as being relative to the high 5th string of the banjo.
Making sense? Here is a tab example of the transmogrification in action.
The first 2 measure of Cripple Creek in banjo tab...
And those same 2 measures converted for open D tuned guitar...
How's that? The idea is essentially treating these strings on the guitar
like these strings on the banjo
And then treating the 1st string on the guitar like the 5th sting on the jo.
For a full song example lets try a little of the old Blackberry Blossom.
Here is a standard melodic style banjo version...
And here it is converted for open D tuned guitar (added some harmonic strums but otherwise transferred directly from banjo)...
Here is a vid of that Blackberry Blossom arrangement on guitar...
Soothing, ringing stuff (a little string noise but what the hay).
You may have noticed that the 6th string on the guitar is not used at all. This is simply because thus far we have only been transferring directly from banjo and the 5 string banjo has 5 strings. If you want to make use of the low string for whatever purpose (probably to provide some harmony/ bass) it is right there waiting to be used. This method allows you to transfer banjo arrangements directly to guitar but once you have done that you can alter them for their new environment as you see fit.
Also, if you want to keep things in their original banjo key you can use the capo. If something is uncapoed on banjo then capoing on the 5th fret of the guitar will make it make it match. If you are capoed on the 2nd fret on banjo then capo 7th fret on guitar.
Hope that proves helpful/ fun for some people. It may be a bit of a headful to get down at first so take your time and as always don't hesitate to write me with any questions.