A problem that sometimes arises. The solution is simple, but it is hard to find, so I though I will write it here, such that other Googlers will find it.
You can simply do this by adding a
policy-rc.d-script. That is, create a script /usr/sbin/policy-rc.d returning 101, before installing anything.
When using packages, the above Link sais one must use the alternatives-System, which sounds plausible.
Well, I have learned that today. It is always interesting to learn something new.