The NetBSD i386 install floppy includes neither a dialer nor pppd.

It does contain tip and slip (and ppp is in the kernel) which can be
used for installing via a serial port.  (But see below.)

   If I remember right, the i386 NetBSD kernel which comes on the install
   floppy doesn't have serial support built in.

From sys/arch/i386/conf/INSTALL:

com0	at isa? port 0x3f8 irq 4	# Standard PC serial ports
com1	at isa? port 0x2f8 irq 3
com2	at isa? port 0x3e8 irq 5

Or did you mean something else?

   I installed on a lap top sans NIC and CD-ROM.  With FreeBSD I used the
   single boot floppy and did the rest of the install through a serial port.
   With NetBSD I had to write quite a few floppies and sit in front of the
   machine swapping floppies.

No real need for this.  The problem is that sysinst does not let you
configure the slip (or ppp) interface.  PR install/8344 (and a related
one PR install/8349 for tip) lets sysint present the full list of
interfaces so that you can configure and use slip or whatever.  The
real solution is to integrate that functionality a bit better, but at
least this will enable one with a bit of knowledge to get through the
install from a serial line easier.

Cheers,
Brook