In my /opt/bootlocal.sh, I have this entry:
/opt/eth0.sh &
My /opt/eth0.sh:
#!/bin/sh
pkill udhcpc
ifconfig eth0 192.168.0.3 netmask 255.255.255.0 broadcast 192.168.0.255 up
route add default gw 192.168.0.1
echo nameserver 192.168.0.1 > /etc/resolv.conf
this has been done via gui
ControlPanel -> Network
opt or opt/eth0.sh has to be listed in /opt/.filetool.lst.