Just more of a how-to question than anything.
I want a user (or a particular set of users)'s TNS_Admin file to point to a different location than the rest of my users. I'm pretty sure this can be accomplished in DEM but unsure of how, exactly.
TNS_Admin is a variable used by Oracle, correct? You can have DEM run a login script/command and condition it to a security group. Setx command can be used to set variables for the user session. For example "setx="pathToFile"