The filer is in FreeBSD's ports collection:
http://www.freebsd.org/cgi/url.cgi?ports/x11-fm/rox-filer/pkg-descr
Warning: the FreeBSD port does CHARSET=iso-8859-1 before running the filer, which prevents it from working in other locales.
See this thread for details.
The filer is in NetBSD's pkgsrc collection at:
/usr/pkgsrc/sysutils/rox/
See also:
ftp://ftp.netbsd.org/pub/NetBSD/packages/pkgsrc/sysutils/rox/README.html
The filer is in OpenBSD's ports collection at:
/usr/ports/x11/rox-filer
And also as a package from the FTP mirrors:
http://www.openbsd.org/ftp.html