You can login to the router via ssh create the vif then setup the pppoe
set interfaces ethernet ethx vif vlan-id
set interfaces ethernet ethx vif vlan-id pppoe <Hit Tab Key.
set interfaces ethernet ethx vif xxx pppoe access-concentrator default-route firewall ipv6 multilink redirect traffic-policy bandwidth description idle-timeout local-address name-server remote-address user-id connect-on-demand dhcpv6-pd ip mtu password service-name