Python is the ideal route to take as it has good xml support.
Here is a cap that will load the map that Candescence posted in the previous post.
http://dl.dropbox.com/u/5426011/examples2/tilemapLoad.cap
made in 0.99.96
Be sure to put the cap in the same directory as the map. Also you might need to install python because the xml modules aren't included in construct.
That works very well. A much more elegant approach then I took. I managed to get a result but without the module so my code was much longer and messier. Python has an XML parser? You learn something new everyday!
However, irritatingly, alpha doesn't work because Construct doesn't seem to like the way Paint.Net saves alpha. I had to remove the black stuff manually. Ugh, what a pain. Don't use Paint.Net for alpha in PNGs, folks.
Edit: Or GIMP either, apparently. God dammit. How the hell do you get proper alpha right off the bat with these things?
Now, the next main problem to make this viable is Z-Order. In other words, layers. Oh, yeah, and collision, I forgot. You either want some things to collide, or some things to not collide, basically...
... Then again, for collision, you could just have a second tileset for collision stuff. That works well. Z-Order is still a problem, though.
Edit: Also, you want to be able to work with multiple tile sets at once, and by consequence, multiple sprites. So, basically...
I managed to get collision working in my script, but it basically involved cloning the tileset and adding the 'Solid' attribute to it. I then added a python list which had all the values for solid tiles and ran a simple condition which decided on which sprite to draw. And it seems that if you import an image by splitting it, it ignores the transparency :/
Unfortunately, creating a tile editor through Python just isn't a viable method if you don't know Python or want to create a semi-complex game. For a truly flexible approach, one needs to create a plugin which is able to add the individual objects into the layout editor as it allows for more flexibility, but that's no easy task...