ALIAS command exists as script command but doesn't exist as SDK function.
I think I can easily add a new SDK function but even if you will be able to ALIAS thinBasic main flow control keywords you will not be able to change they syntax
FOR will remain FOR and DO will remain DO even if you alias them
And you will not able to ALIAS FOR into DO because DO already exists. ALIAS can create "new" aliases.

Ciao
Eros