[lynx] customising network initialisation at bootup time

[baldyeti]

Under 8.04 I had inserted a little script as
/etc/rcS.d/S38_ether_switch in order to customise
the /etc/network/interface file before eth0 got up.
I need this because sometimes I'll start the regular
ubuntu, and sometimes it'll run under windows with
the help of the wonderful colinux. This is not working
anymore since I updgraded to 10.04. Well in a sense it
still does, as I see the correct version of the file is
being activated at boot time, but probably the new
startup system (not sysv anymore) starts the network
before my hook has had a chance to establish an alternate
interface file. Can someone suggest how to adapt the logic?
Note that virtual networking from colinux still works fine,
I just need to "ifdown eth0; ifup eth0" which is cumbersome.