Because you deleted it while I was replying, and all that testing shouldn't go to nothing.
This should work:
1. Go to C:\Documents and Settings\YOUR ACCT\My Documents\EA Games\The Sims 2\SC4Terrains
2. Copy Pleasantview.sc4
3. Go to C:\Documents and Settings\YOUR ACCT\My Documents\SimCity 4\Regions\Downloads
4. Paste.
5. Go into SC4.
6. Click on a small-sized blank city you don't care if you lose.
7. Click the icon that looks like a PC (Import City)
8. Click Continue
9. Click on the Downloads folder, then on shood5
10. Say hello to Pleasantview. Open it, change it, Copy it from your region when you are done and put it back in the \SC4Terrains folder.
Needless to say, you can do this with any terrain you want to edit.