well, the different tuning only requires that you drop your A string down a step to a G... so if you want to play it without retuning, just play anything on that string two frets lower... for example if it says to play on the 5th fret, just play the 3rd, and if it says 3rd fret, play the first. if it has anything lower than the second fret, like it says to play it open, you can play it on your low E string, if it says to play open, you can play the third fret of your 6th string, if it says 1st fret, play the 4th on the 6th string.

that'll work for this song, because after brousing through the tabs I see it doesn't have you play anything on the 6th string. of course, it'd be so much easier to just retune, you only have to retune one string, so as long as you have a tuner, or a piano/keyboard or something to tune off of, it should be really easy. heck if you wanted to, you could just tune your 5th string to the 3rd fret of the 6th string rather than the 5th in standard tuning.