Werner Kuehnert suggested that I try the iij-ppp package
(ftp://ftp.iij.ad.jp/pub/network/iij-ppp0.94beta2.tar.gz), which looks
like it'll do the job. It supports BSDI's BSD/386 1.1, FreeBSD-2.0,
and NetBSD-1.0, but it should be really easy to make it work with
NetBSD-1.1 (it comes with a patched NetBSD-1.0 tun driver... I
probably just need to make the same patches to NetBSD-1.1's driver)

I also got a couple of emails asking where I found "dp"... the latest
version can be found at ftp://phoenix.acn.purdue.edu/dp/dp-4.0.tar.gz

Name: Dave Huang     |   Mammal, mammal / their names are called /
INet: khym@bga.com   |   they raise a paw / the bat, the cat /
FurryMUCK: Dahan     |   dolphin and dog / koala bear and hog -- TMBG
Dahan: Hani G Y+C 20 Y++ L+++ W- C++ T++ A+ E+ S++ V++ F- Q+++ P+ B+ PA+ PL++