Maybe I should have titled this article: How to reproduce a tune on the DS-10? but it doesn't sound as good.
Reproducing a song can be pretty overwhelming especially if you are not too good at isolating tracks (lead, bass, etc) within a song and, most importantly, if you are unable to figure out the notes within a track.
Well, don't despair, because there's a way to do it rather painlessly.
First, you need to find the midi file corresponding to the song. For that, go into google and type something like "visage fade to grey midi" if you want to cover this overly famous 80s anthem by Steve Strange's Visage. Note that there exist search engines just for midi files (google "midi search engines" to find some). Now, don't get your hopes too high because there's definitely not a midi version of every song ever made but if the song is/was a hit, it's likely there's gonna be one. There are wav to midi converters out there but I am not too sure how well they work at isolating the tracks (probably not too well).
Second, once you have the midi file, you need some software to load the midi file and show the notes (pitch and duration) for each track within the song. There are quite a few programs that can do that but you have basically two kinds of midi tune loaders: those that show the tracks sheet music style and those that show the tracks piano roll (letter notation) style. As a side note, it's kind of fun playing midi files because they sound like tunes that were made on 80s computers.
If you are very familiar with sheet music notation, well, you are probably not reading this but I would still recommend NoteWorthy Composer from NoteWorthy Software. It's not free but the evaluation version is. Finale NotePad from Finale can do it as well (the Finale Reader is free download). If you want to go that route, you're gonna need to "translate" from classic sheet music notation to so-called letter notation in order to enter all that data into the Korg DS-10 sequencer.
Why bother with all that extra work when you can load the midi tune and get the tracks in letter notation directly? I know Able Midi Editor (free evaluation version for 20 days) from Widisoft can do that but there are probably many others (let me know of free and good alternatives).
Finally, you need to convert the notes and durations given for each track to the DS-10 sequencer and, most importantly, figure out how to synthesize the sounds for each track with just 2 oscillators. The latter is really the fun part (I think).
Is it worth doing? You'll be the judge on this. It's not very creative but I think you can learn a few things in the process, like ... how to layer tracks to create a song (I think it's important). As they say, you should always learn from the masters.
PS: it is usually frowned upon to do covers based on midi data. Obviously, it is much more interesting/challenging to do it all by ear, assuming you can, eheh.