Adam, if you went to the Small Teeth Pass, killed the Ankhegs and then saved your game this mod can't be used until you start a new game. Your progress is included in your saved game files. So, if you cleared out the map for area 1700, the game won't check to see if there are any changes to that area. When you start a new game the mod will replace the original files.
However, if you visited Small Teeth Pass but did NOT save your game, I might be able to help. BG keeps certain files in a cache. So, when you visit an area a second time, the game checks the cache first and loads the area from the cache. Note that reloading your saved game has little to no effect on the contents of the cache. The cache is located on your hard drive here: C:\Program Files\Black Isle\BGII - SOA\Cache\Data (assuming a standard installation). You could use Windows Explorer to get to that subdirectory and erase a file called AREA1700.bif. This will force the game to check the override directory and load the mod area. Basically, if you visited Small Teeth Pass and then installed the mod, the game will constantly load the version of Small Teeth Pass in your cache that features the ankhegs. But, if you delete the cache file, the game will now load the version that features dragons. Again, if you wiped out the ankhegs you'll have to start a new game to see the dragons.
I hope this helps. Tell me what you think of Improved Small Teeth Pass. This is a very simple mini-mod I ceated that takes a boring area that most people skip and makes it challenging. With a lot of tactics and a little bit of luck, you should get some gold, red dragon scales to make armor and over 180,000xp from the monsters.