TinyCore 9.x goes back a bit.
IF MEMORY SERVES... PHP5 and PHP7 were both available for the ARM back then. Install one or the other.
You DO NOT need the apache PHP support installed if you're not going to use a web server.
Once done, go to the command line and enter:
php -v
If successful, which it should be, it should show you the version information regarding the PHP version you installed.
IF SO, let's say you had a script you wanted to run manually in the shell (as CRON would be doing)
php /place/to/MyPHPfile.php
If THAT is successful (which again, it should be) you then take the same line and enter it in as a cron task/tab and you're done.