WL-500g can do wirless brige thanks to WDS feature, but the WGR-614 doesn't support this protocol, so you can't do a wireless bridge between this two router.Can the WL-500g solve the problem to bridge the two networks together wirelessly?
If you don't want to change your hardware, you're only solution is to link the two devices by a cable.
If you have some money you can buy another WL500g (try deluxe version ) or any other AP that support WDS too.
By the way, for owning a WGR614v5 before my wl500gx, I can assure you that this router is really a piece of crap, and I suggest you to share your Internet connection with the wl500g instead.