Limiting Terrain size when using a FractalTileLoader

I am currently making a game that will (hopefully) end up first person shooter. Since I don’t want to create a ton of height maps (I am more or less doing it alone), I want a random heightmap.I like the FractalTileLoader, it makes nicer terrain than all other HeightMaps, but it has one problem. How do I limit the size of the map generated, I don’t want players wandering off who-knows-where in the middle of a deathmatch, so how could I limit the size to, say 512 while still having the nice gerneration of a FractalTileLoader?