[TYPO3] Extensions shortcut possible?

[Ronald Wiplinger (Lists)]

I have installed on a web host typo3 and now I want to install a second
(actually a lot more).

I used the directory structure:

/  root
/--/ web root
/--/--/typo3 site
....
/--/typo3_src-4.2.1   (parallel to the web root)

and I made sym links to the typo3 site

Is there a way just to copy extensions from one installation (on the
webhost locally) or even make sym links so that I avoid to upload them
again?

Sym links would be even better (???) since it would update the all sites
at once.