If you go into Radio Shack or WalMart look for a three line phone to wall mount jack jumper, i don't have one handy to check though and i think they might be flipped. The Yaesu cable if you hold the ends side by side the wiring is exactly the same. I just grabbed one here and its from left to right with the tab up, contacts down....
White
Brown
Green
Yellow
Black
Red
Just make sure both are wired exactly the same and you will be ok. Not all places carry the six pin three phone line cords, they are generally used in business phone systems more then residential.