Can anyone tell me how to configure the onboard WiFi for the RB751 or RB951 router with a DSL PPPoE client connection? Thank you!
Read the wiki, there are examples and diagrams for this exact scenario.
The method below will be used to establish a PPPoE Dialup via your Bridged nor Routed ADSL device
http://wiki.mikrotik.com/wiki/How_to_Connect_your_Home_Network_to_xDSL_Line