To install the Linuxulator, pick a piece of software that needs Linux mode and install that instead. The Ports Collection is smart enough to realize that a piece of software needs Linux mode and chooses the appropriate pieces of Linux to install. For example, I use Adobe Acrobat Reader (/usr/ports/print/ acroread7) to view PDFs. Installing this port triggers installation of Linux mode.
The port downloads a large number of Linux system files and installs them under /usr/compat/linux. A Linux program uses this userland rather than the FreeBSD userland.
The port also loads the Linux mode kernel module. To make FreeBSD load that module automatically at boot, use this rc.conf entry:
That's it! You should now be able ...