You got 3 options: Perl, PHP, SSI
I think Perl is less popular than the other two.
Does your host support PHP/SSI?
Make a file called test.php
Make sure the file has executable permission set in addition to read (chmod 755) (not sure if read is even needed...)
Visit the file with your browser. Either you get what you typed -> no PHP, or you get other stuff.
Stick this somewhere in your HTML file and see if it works:
<!--#echo var="DATE_LOCAL" -->