Customize all resources *.sublime-* down to project level

Hello,

Best Editor. Ever.
I have a request about building system on Sublime Text 2. It happens in my organization to develop C applications for micro-controllers. We have different compilers and linkers and normally different building options to manage.
We have up to half dozen of most used tasks (building variants) for each project. Generally speaking we have few categories where a project falls into.
The most obvious difference is on the "file_regex" property when dealing with more compilers.

Now, it's possible to specify "build_systems" inside the sublime-project, but it does not bring to a desirable result.

Another problem is the key binding for building tasks to launch. I'm not able to assign this binding at project level.
For example the Ctrl+Shift+F9 should execute different commands on different projects, given the purpose of the operation is the same for consistency.

Here is my desire
I would like to specify at project level key combos and building variants like they would appear if done inside the user .sublime-build file.

I thought it was possible to customize all resources down to project level by simply adding the associated .sublime-* file inside the project root (aka where the .sublime-project is stored), but I'm not able to make it work.

I googled enough to think it is not possible yet, maybe I'm wrong.

Thanks!