quail input methods and conversion functions

[Uwe Brauer]

Hello


In ancient pre Mule times, there was iso-unacentuate which for 
example would translatex ä to "a


Does something like this exist for all, or some quail input 
methods?

For example take greek-ibycus4 then
a) gives ἀ


So the function I am looking for would 

a) <--> ἀ

I think I know how to do that for this particular input method, 
but I don't want to reinvent the wheel. So any pointer would be 
wellcome.

Uwe Brauer