Text editing: switch to Override mode

You didn't give any examples, but if this is your use case:

somefunction("onestring", "otherstring")
^^^^^^^^^^^^^^^^^^^^^^abc^^^^^^^^^^^^^^^

Then you're asking for a hotkey to move your cursor from position ab to bc, which can be accomplished by hitting → (right arrow key) once. Any hotkey combination would result in more key-presses than this and therefore not be beneficial (unless you want to avoid moving your hand off the home position, in which case you may want to look at ViMate).

For finding hotkeys the Textmate bundle contains a function called Show Keyboard Shortcuts, which lets you do exactly that. Hit ^⌥⌘K to quickly access it.

You may want to have a look at /Users//Library/Application Support/Sublime Text 2/Packages/Matlab.sublime-package. It's a simple ZIP file containing a bunch of XML (Plist) files.

In the Sublime Doc for syntax definitions you'd be able to find a documentation of how to create (and edit) syntax definitions.

For an example have a look at the perl syntax definition, it contains a key named "firstLineMatch" which is not used in the Matlab syntax definition. But you could add one and create a file magic for/in your Matlab files.

Update : I just gave it a go and it doesn't seem to work. Do be fair TextMate can't do it either.

Update 2 : After some more investigation: The question about firstLineMatch came up in the Sublime Forum. The file extension is taking precedence over firstLineMatch right now. So there's not much that can be done. With firstLineMatch working you could do nice things. And this would mean that no file magic would be necessary since the syntax of Obj-C and Matlab files is different.