ok, so rootsh is required.

what a lucky guy i am that all the repos are down right now... xD

You have to install the rootsh package, I think it is. You may have trouble doing that with repositories down, though.

ok, i have rootsh now, sudo gainroot works.

the problem is: what path do i have to enter with dpkg -i?

i put the file on 2 locations.
location 1, as seen from the filemanager, is: Nokia N900/file.deb
location 2, as seen from the filemanager, is: Sdhc1/file.deb

now i tried dpkg -i Nokia N900/file.deb
and i tried dpkg -i Sdhc1/file.deb

also tried dpkg -i media/Sdhc1/file.deb because i read that memory-cards need to have media/ in front of them.

nothing of this works, all i get is "no such file or directory"

Location1 should be /home/user/MyDocs/file.deb
Location2 should be /media/mmc1/file.deb

i just (10 secs ago) figured that out

i just dont understand why the terminal-path is called mmc when the card itself is named sdhc1.

i still have to learn a lot about linux...^^

The card name (sdhc1) can be changed, and is user-specific. The mount point needs to be fixed though, otherwise it'd be impossible to write apps to access it.

i see the point.
but as "deep" as terminal may be, its still user-controlled. so why not use the names the user has given to devices? internally, it can still work with the fixed names....

whatever, i'll get used to it.