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 declare bridge 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 could 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,ppp,keyboard,bridge,dnscache,weblet

The last two lines ("default linux ... dnscache,weblet") must be typed as a single one in syslinux.cfg