The default "dead" keys do not require root. That is built into android and is default.
For example to get any letter with an Acute accent type ALT + e and then a letter. It will place the acute accent over it.
To get the Circumflex accent type ALT + i and then any letter and you will get it over the next letter that you type.
No root required.
ROM: Carbon Rom for now
ASUS Transformer TF701
ROM: CM 10 something or other.