Here are the instructions from Vurt's Groundcover page:

How to make Groundcover mod compatible with landscape altering mods.

So you've installed the Groundcover mod and you've noticed an area in the game with floating vegetation. This means you've got a mod activated that alters the landscape, unfortunately this makes my mod incompatible. Fortunately there's a way to fix this, and it's actually quite easy.

Let's say you're in-game looking at the floating grass, here's what to do:

* Go into the console, enter TG then enter. Now you will have the position of the cell where floating vegetation is. Write the position down, or take a screenshot.

* Start TES Construction Set. Go to "File", "Data Files..." and tick Morrowind.esm and Vurt's Groundcover - BC, AI, WG, GL.esp, click "set as active file". You might also want to tick the mod that is affecting the landscape if you want to see how it alter the landscape/grass.

* Click "World", "Go to Cell", enter the cordinates you wrote down, hit enter. This should take you to the affected cell.

* Drag and select the whole area with floating vegetation, it does not matter if you select rocks, trees or houses. Hit the Del key. If you're deleting a whole town for example you'll get a lot of annoying messages where you're supposed to click ok, just hold Enter to skip through all those messages.

* "File", "Save"

* Download TES3CMD: http://mlox.googlecode.com/files/tes3cmd-0.37p-2011.05.23.7z

* extract this exe to the root of c:\ and also copy Vurt's Groundcover - BC, AI, WG, GL.esp to c:\

* copy this text (ctrl+c): tes3cmd delete --instance-no-match GRS_ "Vurt's Groundcover - BC, AI, WG, GL.esp

* Click the start button, write: command prompt in the search field, click its icon.

* enter cd.. (hit Enter) untill you reach the root of C:\ where you copied the .esp

* Right click in the window, paste, and hit enter. This procedure will undelete everything except the floating grass that you removed.

* You now have a compatible .esp. There's no need to ask for my permission to share this file.

I've made it as far as "extract this exe to the root of c:\ and also copy Vurt's Groundcover - BC, AI, WG, GL.esp to c:\". I'm not exactly sure what the root of c:\ is. Is it the main Morrowind folder, where the Data folder and Morrowind Launcher is? The next line, "copy this text (ctrl+c): tes3cmd delete --instance-no-match GRS_ "Vurt's Groundcover - BC, AI, WG, GL.esp", is a bit confusing too. I'm sure it's pretty simple to do, I just don't understand what to do exactly. Any help?