The usual command that I\'m familiar with is chmod +x, which would allow all users to excute that program/file.
It\'s done by going into the command line, a console, and typing chmod +x [whatever the ps file is].
To actually install planeshift, you have to be under root, and to execute the file, you\'ll need to set the permissions so that your user (normal) can execute it, like using the command above.
Second option would be to include your normal user within the \'games\' group, as the installer is supposed to set the permissions for the games group as well as whoever installed it.
As far as I know, there shouldn\'t be any problems if you install PS to a different folder than the default one, heck, mine is anything but default.