Specifying different pinentry based on caller?

[Tim Chase]

Is there a way to specify which pinentry program should be used based
on the calling context?  When using a GUI program like Claws Mail, I'd
like to use the graphical pinentry, but I'd prefer to default to the
terminal pinentry for everything else.

Poking around, I've found ways of changing this globally, but am
unsure how to go about specifying it on a per-application basis. 

I imagine that it would take some combined effort between gpg (to
allow the pinentry program to be specified via the command-line or
environment) and the calling program (to specify arguments).

Any tips to get me headed in the right direction would be appreciated.

Thanks,

-tkc