Until July 2000, there were two ways to set file permissions: From the Terminal, or with Chris Herborth’s SetPerms add-on. With later versions of OpenTracker, however, you can set permissions from the Tracker directly.

The permissions configuration panel lives in the Get Info panel. To access it, select a file and tap Alt+I (or right-click | Get Info). You’ll see a „Permissions“ widget at the bottom of the panel, which will also let you establish user and group names for that file (though user/group options aren’t currently working).
If you don’t see this widget, grab the latest version of OpenTracker. This feature, like most OpenTracker developments, will probably be included in future releases of BeOS.