Dig a cliff to make a building

I need help, I need to place a building in a cliff,just like if you place the enchanted mine in a gold mine. The problem is, I dunno how
Here,I post a picture of what I want.

Help will be rewarded, and will be given credits if I use this in my maps.

create a doodad via triggers at your beloved place

No,that wasn't what I was looking for, what I need is somthing to build in a building,like the enchanted mine,( and then research or create units,whatever.)
I can change the model of the gold mine, and building's, but I was asking if there is a better way not too complex( If there are not, well, I'll try the other way...)

oh, then you can place the doodad and an invisible unit which does everything your building has to do at the same place

He must be able to build it, dude. Afaik, you can't do such a thing, due to cliff pathing.

then set the dummy-buildings collision to 0. the position fo the dummy is not important, as long as it's near the cave/whatever.

you've only to trigger it properly

EDIT:

forget what I said about placing a doodad

you can't place cliff-caves via triggers, and when you give the model to a destructabe or unit, it will have a white texture
--> you have to make a model-edit (sides) and add some textures (removing the white parts)
--> your building is a normal building, you've not to mess around with destructables/doodads
--> you've only to trigger where you can place this building
if you need help with the trigger, you can ask me

You can change what texture it uses when used as a destructable. Which index to change? No idea.

Sorry,I was having exams this week,so I couldnt review this.
yes,I'm changing the texture of the cliff,it's a very simple model edit. What I do really need help is in the triggers. Also,can you place a doodad in a building without modeling and geomerging it?If so,I need help ther too. Thanks

??? ??? ??? ??? ???

if you need help, you've only to ask

yes,any help would be welcome :). Thanks