I only have the alterrev version of MW2, which looks like this:

 

Can I install 4d1 on this version? Because I don't want to download it again, because the skidrow version is 10GB... (internet bandswitch)

Never done it myself but from what I've seen: yes.

 

4D1 has a very small file size, so give it a shot, nothing to lose.

Try using number 38 in this thread: viewtopic.php?f=7&t=4144

That should work.

If you use the big DOWNLOAD button, then yes, since the updater stores it's files in appdata, away from the actual game files.

I did it aswell before but it was kinda Fu*ked.

Y U no look HERE?

(No. 38)