Wireless Routers incorporate a "Wireless Access Point" to which Wireless Network Adapters connect.
However, two Wireless Access Points cannot communicate directly (although two WiFi Adapters can in "Ad Hoc" mode). Therefore, your WAG54GS isn't going to connect wirelessly to the DIR-615 to provide an ethernet connection for the printer.
What you require is a "Wireless Network Bridge". This is the opposite of a Wireless Access Point and allows a "wired" network (your printer) to connect to a "wireless" network (your D-Link router).