> What am I doing wrong. Does NetBSD support ppp, or am I doing something
> wrong?

Yes, NetBSD supports PPP. It is included by default (and I often use it).

Have a look at PPP and ISDN documentation at
http://www.netbsd.org/Documentation/network/

Plus a google search should turn up other guides and howtos, like:
 http://www2.giganet.net/~mark/NetBSD/ppp.html
 http://www.bsdtoday.com/2000/July/Features237.html
 http://www.resort.com/~banshee/Tech/ppp.html (maybe too old?)
 http://www.mclink.it/personal/MG2508/nbsdeng/chap-net2.html

For multilink PPP, maybe look at the net/userppp package.

Good luck,

   Jeremy C. Reed
   http://bsd.reedmedia.net/