Installing 2.5 with 2.4?

[John Machin]

Duncan Booth wrote:
> "John Machin" <sjmachin at lexicon.net> wrote:
>
> > 1. You need to set your path manually. A BAT file called pypath.bat
> > placed somewhere on your PATH and containing:
> >     path c:\python%1;c:\python%1\scripts;%path%
> > might come in handy. Warning: this is best used once each time you open
> > up a command window; it's cumulative (Windows is not smart enough to
> > remove duplicate entries) and there is a an upper limit (I believe) on
> > the size of the PATH.
>
> Windows is only smart enough to avoid duplicate entries if you tell it
> to do that. e.g.
>
> PATH c:\python25;c:\python25\scripts;%PATH:c:\python25;c:\python25\scripts;=%
>
> will add the two Python 2.5 folders to the head of the path without
> duplicating them.

Wow .. I didn't know that! What's the syntax? Something like
%variablename[:oldtext=[newtext]]%
?
Where is this documented?