[ESS] Is there a good way to set shell variables before running S+6?

[Tim Hesterberg]

Is there a good way to set shell variables before running ESS's S+6
command?
I don't want to set shell variables and export them globally; I want
them to apply only to the process from which S+ starts.

I've thought of a couple of ways:
(1) start an ordinary shell, set the variables, start S+,
then use
	(ess-remote)
to convert that shell to an ESS buffer.

(2) Write a shell script which sets the variables and starts S+;
then set inferior-S+6-program-name and inferior-ess-program to the
that shell script.

Is there a cleaner way?
Is there something in the style of:
	inferior-ess-start-args
	inferior-Splus-args
but for setting shell variables rather than command-line arguments?
I didn't find anythingin the ESS manual.

Thank you,
Tim Hesterberg