Since the acrotex bundle does not ship with TeX Live, it is probably wise to put it in your 'personal' texmf tree. On GNU/Linux OSes, this is probably located at ~/texmf (which is short for /home/<username>/texmf). If you are unsure, you can check with the following command:
kpsewhich --var-value TEXMFHOME
(This returns for me /home/jon/texmf.)
The thing to remember is that your local texmf tree must mimic the system tree in order for things to be found. Thus, most 'local' packages for LaTeX should be put in the appropriate directory, namely:
~/texmf/tex/latex
So, in the case of creating an acrotex directly, you can type:
mkdir -p ~/texmf/tex/latex/acrotex # where -p allows you to create multiple directory levels all in one go
Now you can put the unzipped contents of the acrotex bundle there. However if it comes with documentation, you might want to put the documentation in the corresponding location; so:
mkdir -p ~/texmf/doc/latex/acrotex # try: kpsewhich --var-value TEXDOCS
and copy the docs to that directory.
If you are unsure what the sub-structure of ~/texmf should look like, you can compare the system structure at (for TeX Live 2012):
/usr/local/texlive/2012/texmf-dist
It may also be worth noting that many (though not all: e.g., acrotex) packages are also available in as a .tds.zip, which make it very easy to install at the base of any texmf tree; e.g., in your local tree:
unzip -d ~/texmf/ <package>.tds.zip
mkdir -p ~/texmf/tex/latex/acrotexand put everything in there. Alternatively, you could put it in/usr/local/texlive/2012/texmf-dist/tex/latex/acrotex, though of course you'll need to make the directory withsudo mkdir, and then refresh the database with something likesudo texhash. – jon Apr 06 '13 at 02:45