you could probably just make a big 64tiles x 64tiles image to lay down on a level and use setshape2 to define how parts of the image work.
this could be both a good and bad thing, depending on how many levels you plan on having and is probably a hackish method to achieve what you want..
TServerNPC.setshape2(int, int, obj) - enables tile-based blocking behaviour. Parameters are tile width, height and an array of tile types; you have to set it on both server-side and client-side to make it blocking on both server and client
Here is some information about setshape2 and tiletypes
http://wiki.graal.net/index.php/Tiletype