Install server admin tools 10.6.8 on same system fails

It's not entirely clear to me what you're doing here, so (like over in that other thread) I'm going to guess.

OS X Server ships with the server tools in 10.6, and the versions of the tools are maintained by Software Update.

You can want and need to install Server Tools 10.6 only on an OS X 10.6 client system. Not on OS X Server.

Now if you're progressing along the usual path of Server Tools confusion apace and might soon be looking at the version numbers displayed by the various tools and thinking you need an upgrade, well, you don't. (Yeah, I bumped into that one, too.) The versions that are displayed by the various Server Tools applications are confusingly not the same as the Server Tools package version, and tend to trail the packaged version. Confusing? Yes. Poor error messages out of the Server Tools installer? Yep. Been there. If Software Update invoked on the OS X Server box is happy, you're good to go.

lets see if I have this right

you've updated your machine to 10.8

you need to manage 10.6.8 server

You can't install 10.6 server tools on 10.8 as you've found

the only option is to manage 10.6 server is with

ARD or VNC or screen share from your 10.8 machine to remotely control the server tools on the 10.6 server

You need to use ARD (as you all ready have it) on your 10.8 machine to remotely access the 10.6 server tools on the 10.6 server, which are all ready installed on the server.

You do not install the Server Tools kit on OS X Server 10.6.x.

You should not attempt to install the Server Tools kit on OS X Server 10.6.x.

There should be no way to install the Server Tools kit on OS X Server 10.6.x.

The Server Tools kit installer will (should) prevent this attempt, too.

Why? Because this Server Tools installation is not necessary.

You already have Server Tools installed on OS X Server.

The Server Tools package is a component of the OS X Server installation, and already installed on OS X Server, and already maintained as current by OS X Server.

On OS X Server, look in Applications > Server — same spot as you'll find the tools, when the Server Tools are installed on OS X client — for the Server Tools.

Pacifist is good for pulling apart kits and recovering pieces and parts, but I'd prefer to stick with the Apple tools and installers where I can, and with backups and related. It wouldn't be my first stop here, but this is your system.

I'd get a backup or two, and would then first install the OS X Server 10.6.8 combo update, and then (if that fails to resolve this) reinstall the original OS X Server distro onto the box again, and then patch to current.

I'd consider going as far as a full migration" of this configuration; start over and reload the existing data.

Why the combo update or the reinstall? If an administrative user has been deleting hunks of the operating system, then other file deletions and "oddities" are potentially also in play here, too. "Rearguard" fixes and file recoveries are never "fun", and the aggregate effort involved can exceed starting over.