That's what I did to start with (see my other thread) and couldn't get it to connect. So whilst I'm waiting to be able to try it on another line, I thought I'd try using it as just a router, letting the Netgear's (which I know does work) modem do the syncing.
If your provider only supports PPPoA, then it isn't possible to configure a device that has an ethernet uplink to use PPPoA.
The typical Ethernet MTU on a PPPoA circuit is 1500, plus the PPPoA headers.
The typical Ethernet MTU on a PPPoE circuit is 1492, plus the 8 bytes for the PPP header, so it can fit inside a standard 1500 MTU ethernet frame.
But it isn't just the MTU mismatch, but the way the headers are applied is different. The only devices that can use PPPoA are devices that have ATM interfaces, like an xDSL line or lines.
You really should talk with your provider, and ask them if they can support PPPoE on your line. If they can, they'll make some changes on their side, and your setup should work.