You will have two computers - SheShed computer and home computer.  Download your ProSeries program to each computer.  Use some type of external drive to store the client files so you can easily move from one location to another without going through the backup/restore process.   That's it. 

standalone just means you aren't networking the two computers 

edit:  George answered pretty much the same while I was typing this and then sidetracked talking to a client