Is it possible to modify files on sd from PC without unmounting? Motivation:

As I currently got started to put some media (music,ebook,etc..) I need to organize (add,modify,move,rename) files often but also see if the android apps are still recognizing my files properly.

As file transfer and organization is much faster on PC I plug in the USB cable and do what I want. Unfortunately android unmounts the sd memory so my apps e.g. Gallery wont be able to see the data. So I have to unmount on my PC and then nasty long media scanning takes places, and finally I can see the files within android. What me disturbs is the tedious mounting/unmounting process.

Question:

Can't I just simply alter files on sd memory over USB/Wifi or whatsoever while leaving the sd memory mounted? That would be awesome.
Ahh, I should have known, ssh is the solution. Therefore install an ssh server e.g. SSHDroid then you should usually have sftp and ssh to your phone. As command line tools like sed echo and basename are available even renaming is really easy :D.

The really great thing is you even don't need a wifi around, you can make your own with wifi thetering and SSHDroid will still work, though you have to disable the presence of a network in its options first.

You don't need to root the phone.