[j-nsp] IPSec Tunnel across Internet

[Juniper]

Hi,

I'm new at Juniper world, I would like to know how can I configure an encrypted tunnel between two Juniper M-20 across internet. I have found some examples but they all asume I have an ES or AS PIC. I just want to know if it's possible to configure IPSec with pre-shared keys, IKE, etc...
with just an M-20 with a Tunnel PIC, and how... I'm a bit confused  :-D 

Can anyone help me guys?

Thanks a lot in advance