Hello Hauke,

  HF> http://la.causeuse.org/hauke/slip/ has some
    > information, including a proxy-arp setup. I should
    > probably go and fill in the gaps.

Sadly that link doesn't work for me (404).  proxy-arp would
seem to make sense, since the neither end of the SLIP link
will have an Ethernet MAC address.  The SLIP link is working
well, but I'm not sure how to connect the interfaces.

- Andy Ball