# Create a directory (distinct from $HOME) where 
# the second steam instance will place its files into
> mkdir /home/$USER/second_steam_home/


# Temporarily point $HOME to that second directory for the second steam instance.
#   -userchooser  will prevent automatic selection of the user to log into
> HOME=/home/$USER/second_steam_home/ steam -userchooser


# When developing an application which uses the Steamworks API,
# use the same temporary overwrite to make your application target 
# the second steam instance
> HOME=/home/$USER/second_steam_home/ ./my_application