so I'm asking is it feasible to do this?
No I can see it I can say yes this is feasible.
did a test run to see if I could turn on a light with one jack and 1 headphone cord but didn't seem to work.
This means you have made an mistake somewhere. So:-
1) Post the code you used and use the code tags ( see stick post at start of programming questions )
2) Give a schematic of exactly how you wired it up.
3) Say what you expect the code to do and say what it actually did.
cause most forums I've been on disallow link
Not here they don't.