Linux software won't install were it's told to!

[Benjamin]

Disclosure: I have posted this question on the forums too.

I am still attempting to port Quartus II design software to FreeBSD. I 
am making progress, with the help of this list and others.

My latest problem is strange. I've followed all the shell script 
wrappers to find the actual installation binary that is run. It takes an 
option that lets the user specify where to install (-t <location>).

When I run it thus:

# altera_installer_cmd --source=/usr/ports/cad/quartus_ii/work 
--install=quartus_free -w -t /home/benjamin/some_dir --no_space_check

It installs to some_dir in my home directory, as expected. If I change 
the install path to /usr/local however:

# altera_installer_cmd --source=/usr/ports/cad/quartus_ii/work 
--install=quartus_free -w -t /usr/local/quartus --no_space_check

(the only difference between the two commands is the "-t <location>" bit)

It somehow installs to /compat/linux/usr/local/quartus rather than 
/usr/local/quartus! It is almost as if there is a magic "symlink" 
redirecting certain folders, but it doesn't redirect when I specify my 
home directory.

What could be going on here?