The way I do it:

Put a dummy (or copy the real) Poser.exe into a folder.
Let's call that folder "Main Runtimes", for clarity sake.
So now you have something like c:/Main Runtimes which contains Poser.exe
Now make another folder in there, called "Runtime".
So now you have something like c:/Main Runtimes/Runtime - which is empty.

Let's say you want to install V4
Run the Daz installer for the BASE figure. (Make sure it's the poser file. usually prefixed with dpc, not ds)
Choose the Poser install.
When it asks you where to install, point it at the C:/Main Runtimes folder.
IF it throws a wobbly and moans about Poser.exe, go back, and choose the Daz Install where you specify a location. (It works on mine, but hey, maybe I'm special)
Ignore the initialize things for now. I'll get to that.
Now you can install everything else into that directory. (Elite, Morphs++, Muscle, Creature, etc etc etc)
Each time, ignore the initialize, until you are done.

When you are done, you can either keep it there and add the runtime to your library, or you can move everything to the main runtime, or you can make a new runtime and call it V4 if you want individual figure runtimes.
Ignore the initialize on your desktop. In fact, delete them. They are only shortcuts, but they will point to the wrong location if you move the runtime.
After you have the runtime where you want it, go to the !Daz folder
(Runtime/Library/!Daz)
You should see a file called DzCreateExPFiles.bat
Doubleclick it to run.

So now you have a clean install, with everything initialized, in the location you want.
All you have to remember is to add that runtime to your library, if it isn't one you already have in there. :)

Hope it helps.

PS

I have an install folder with the main figures for exactly this purpose.
I install any new morphy pack into there first.

I install them there, and then copy the bits I want to where I want them. (I don't use the main poser runtime) This way I always have a clean copy of the figures, and a way to add morphs without messing up my real runtime. :)

I'm anal about where stuff goes on my machine lol.

Silke