Best way to strip diacritic signs from HL7 message.

We are interfacing through Ensemble with an application that does not like diacritic signs in text. I have been searching for a way to strip these signs from the HL7 messages that get send to that application. 
The problem in short is we have an incoming HL7 message with e.g. é (or ë, á etc), this goes into Ensemble. In the outgoing message the é should be replaced with an e. 

I have tried solving this issue with the use of a new subtable, which does the conversion as é->e / ë->e etc. This works with (file)streams and also with ZConvert: Write $Zconvert("ë","O","BASCII")outputs "e", where BASCII is the new subtable. I have not found an easy way to use this subtable in Ensemble to strip the diacritic signs from the message. 

What (other) options are available?