Boot a Bering floppy image. Once the LEAF menu appears get access to
the linux shell by (q)uitting the menu. Edit the syslinux.cfg
file and REPLACE the pump entry by ppp,pptp in the LRP= list of packages
to be loaded at boot. Check the Bering installation guide
to learn how to do that.
Your syslinux.cfg file will then look like
(adjust to your tastes):
display syslinux.dpy timeout 0 default linux initrd=initrd.lrp init=/linuxrc rw root=/dev/ram0 boot=/dev/fd0u1680:msdos PKGPATH=/dev/fd0u1680 LRP=root,etc,local,modules,iptables,ppp,pptp,keyboard,shorwall,ulogd,dnscache,weblet
The last two lines ("default linux ... dnscache,weblet")
must be typed as a single one in syslinux.cfg
The ppp package is provided on the standard Bering floppy. The pptp.lrp package is available here. Check the Bering installation guide.