Creating environmental variables during deployment

Hello everyone,

I am using an installer that does not allow me to set Windows environment variables. I am use to using Installshield which has that feature. After doing some research, I found that I can write a script that will create environment variables and have the installer execute the script. I know what needs to go into the script, but can anyone tell me what to write it in (what extension), and how to execute a script?

Thanks in advance

What installer are you using? It's not a secret is it? ;) Better details gets better answers.

I am using DeployMaster.