There is currently no easy solution to do cold storage with BitShares. But technically it doesn't require more than some little python program.
Unfortunatelly, that tool does not exist yet .. Currently, you need to be online to create a properly formated transaction for signing. We are working on this.

I need to setup a cold storage computer.

Whats the minimum ram, cpu, and operating system I'm going to need to run a BTS wallet?

Thanks