Well, EMXP is not meant to be an editor.
It's a converter, a disk (image) utility and a communication tool.
And this makes EMXP already quite a complicated piece of software (from a source code perspective).
While many things are waiting to be added to EMXP, changing/editing individual parameters is not one of them.
And to be honest, I don't think I will consider it during the next... well... few years
I'm currently working on a re-engineering of the existing internal stuff (which is taking an awful lot of time already... much more than I had originally expected) and on extending the WAV-to-any sampler bank construction feature, and will then probably add SP12 conversion/communication support and windows folder support in a later version.
But no editing functionality, sorry.