Wondering if that is in configs?
at deployment time you can specify instance size like this:
$ node_modules/.bin/awsbox create -n mything -t c1.medium
Were you looking for something to change instance-size post creation, or is this what you were looking for?
$ node_modules/.bin/awsbox create -h
for a list of all flags.
Yes I meant post-creation.
There is no verb to change instances. I'd happily accept a pull request to do so from the command line.
In the couple times I've had to change instance size I've done it through the web console.