You will not be able to do this, because your RJ45 router does not have an ADSL modem to modulate the signal. Your router is expecting to receive Ethernet frames. Typical DSL, in the US, is fed ATM from the telco DSLAM to your router, this has a PVC (or vpi/vci) and is a completely different encapsulation than ethernet. So your router would likely drop all frames because they don't adhere to the standards.
The short of it is, your telco is speking french, and your router only understands spanish.
One option, as you mentioned in the comment, is to bridge the telco modem so it is a layer 2 pass through. It is, essentially, converting ADSL into Ethernet and feeding that to your router. The benefit of this, is the PPPoE COULD be handled on your RJ45 router, and the public address will also live on your RJ45 router. If YOUR router is a Cisco IOS router, you create a Dialer and put the physical interface in a pppoe pool. The dialer is configured with pap/chap, and obtains your public negotiated address.
Another option, is to buy a router with a DSL modem embedded. Since this would likely cost more, I mention it as a second option. An example of this is any Cisco 800 series thats last digit ends in a 7. (E.g. 857, 877, 887 etc)