WordPress MU

hi there,
I have read a lot in this forums, even about the topic I am just starting, still I need some more hints.

I am going to replace an existing site with a wpmu installation and I would like NOT to use a localhost test server, but test on the final server.

How do you usually do this?

###edit###
another related question: is it possible to build wpmu into an existing site, i.e. use the current site at example.com for the main site, then have subblogs i.e. blog1.example.com etc, without even usign the wpmu frontend, just the backend?
I imagine I could use .htaccess in such a way, that the actual wpmu frontend is never "touched" right?

I know the recommended action is to "rebuild" the old site in wpmu but still, if I had to keep the old site, would my plan work out?
I could for example use a spare domain, set it all up and ready, then search through the mysql database for occurances of the testdomain.com and replace by the final domain, then move, would that be the suggested action to take?

Depends on what the existing site is. Is it a wordpress install? Static files? Another blog software? CMS?

You can install mu into a subdomain. Just remember that your blogs will be coming off of that url. ie username.blogs.mydomain.tld or blogs.mydomain.tld/username

the original site is php where the owner played around. now he wants wo extend his site with wpmu, so I'd either have to keep his site and build wpmu around it, or better even reconstruct the main wpmu site to mirror his design and content without disturbing the old site then move it over.
those are the two scenarios I asked for help with, its either one or the other way but I'd prefer to redo the site so where to build and test and how to move it when finished?

or would it be possible to set up wpmu to domain.com/wpmu and leave the current site at domain.com until everything is finished then move the wpmu install to domain.com without the wpmu folder?

what changes would that include? I guess for the move I could just go through the database and replace domain.com/wpmu with domain.com or is it a lot more complicated than that?

What's the problem with a local test server?

Use your hosts file to point the domain to your local copy, and go from there.

Can't show a client any changes made on your local copy. :)

Yeah you can. ;)

...If you take your laptop along...
Or, send it them on a USB stick (xampp)...
Photoshop, that works. Even for adding a missile...

:-) thx for the opinions

Typically, I would think screenshots would be enough during the initial stages to get an idea for what's going on.

Now, if the current site was on a different IP (that's publicly accessible) than what the new one would have, that would be a different case. But, typically, it's usually a good idea to stay away from developing on a live site that's actively used.