i guess i forgot to close this post. What i did is the following.. just these lines did it.
set vpn ipsec ipsec-interfaces interface eth0
set vpn ipsec nat-networks allowed-network 10.0.0.0/8
set vpn ipsec nat-networks allowed-network 172.16.0.0/12
set vpn ipsec nat-networks allowed-network 192.168.0.0/16
set vpn ipsec nat-traversal enable
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access authentication local-users username XXXXX password X123
set vpn l2tp remote-access client-ip-pool start 10.254.254.100
set vpn l2tp remote-access client-ip-pool stop 10.254.254.200
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret XXXX1234
set vpn l2tp remote-access ipsec-settings ike-lifetime 3600
set vpn l2tp remote-access mtu 1024
set vpn l2tp remote-access outside-address xxx.xxx.xxx.xxx
set vpn l2tp remote-access outside-nexthop xxx.xxx.xxx.xxx
