I upgraded mine(678) using minicom. Once the settings were correct in 
minicom as, set by using root, I did
#minicom cisco (where cisco is the name of the configuration file)
Hit enter at the minicom screen and you should get the 
cbos> prompt. Follow the instructions on power cycling the modem then 
upload and configuration from here:
http://www.infomagic.net/pipermail/luna/2002-March/001335.html

I did find that if you hold down ctrl+C before powering back up you are 
more likely to get the correct prompt the first time.

On Fri, 10 May 2002, Eric Richardson wrote:

> Hi,
> Is there a way to get the CBOS 2.4.3 for a 675 and install it with Linux 
> via the terminal port and a com program. I have tried connecting via 
> modem serial port but I'm not really sure how to do the upgrade. I'm in 
> routing mode so I don't think I can use the tftp procedure as the router 
> doesn't have a IP address.
> 
> Any help appreciated,
> Eric :-)
> 
> p.s. I hate to resort to another OS for this task.
> 
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