Is there a way to preseed UCF questions?

I am upgrading several systems from etch to lenny, and ideally I  
should be able to preseed every question. The main problem I'm having  
is with UCF questions (ie should this configuration file be  
overwritten by the package maintainer's version?).

There are some ucf questions in /var/cache/debconf/config.dat:

> Name: ucf/changeprompt
> Template: ucf/changeprompt
> Value: keep_current
> Owners: ucf
> Variables:
>  BASENAME = sensors.conf
>  FILE = /etc/sensors.conf

and

> Name: ucf/changeprompt
> Template: ucf/changeprompt
> Value: install_new
> Owners: ucf
> Flags: seen
> Variables:
>  BASENAME = apticron.conf
>  FILE = /etc/apticron/apticron.conf

But I don't know if it's possible to preseed these at all, let alone  
to preseed them in a way that debconf-set-selections will grok.

Any help is greatly appreciated.


As a follow-up, the other questions I've been unable to avoid prompts  
for is when applications ask which services to restart in order to  
reload an updated library. These actually have preseed values, but the  
installers seem to ignore the debconf preseed database. Here are  
examples of my preseeded values which are I pull in with debconf-set-
selections before they are ignored:

> libpam0g libpam0g/restart-services string cron
> libssl0.9.8 libssl0.9.8/restart-services string ntp exim4 ssh