Multiple gateways, changing Ips

[Marcus Bointon <marcus@synchromedia.co.uk>]

My colocation provider is changing ISPs, and this is going to involve IP
address changes for my server (running OpenBSD 3.1-stable). I only have a
single physical network connection with multiple IPs assigned. To minimize
downtime, they are running both networks in parallel for a while. In order
to set up the new network I have set up new forwarders on my DNS, added the
same hosts to my resolv.conf, got apache ready to receive on the new IPs.
The remaining big thing is to assign the new IPs in /etc/hostname.* and
/etc/mygate. However, if I'm going to be able to run both networks at once,
I effectively need two gateways, one for each network. I've been rummaging
all over the place online and in man pages, and can't find anything that
seems right - I mean, can I just put two addresses in mygate? Or will it
just get confused or ignore the second gateway? Do I need to do some kind of
routing from one network to the other (they don't need to talk to each other
- just to respond individually)? For the actual new IPs in my hostname.*
file do I add the new IPs as aliases like I have for addresses on my
existing allocation? Ah, and of course I need to do all this via remote SSH
only as physical access is difficult.

Help!

Thanks,

Marcus
-- 
Marcus Bointon
Synchromedia Limited: Putting you in the picture
marcus@synchromedia.co.uk | http://www.synchromedia.co.uk