How to change a C-Node written with ei to be a port program?

[erlang@REDACTED]

Hello,

I've got a program that acts as a C-Node written using the most
excellent ei library.  This works very well, but in order to simplify
startup I am investigating the use of a port instead.

Since I now have all this code making use of ei_xreceive_msg() and all
those ei_decode_...() and ei_x_encode_...() functions, is there a way to
write a port program, so that I can reuse most of this existing code?

In other words, how do I implement a port program that communicates
with its parent using the external message format in such a way that I
can use the ei library?

Thanks for any pointers,
Robby