Hiya!
How are you intending to use PHP with Flash?
if you want to create variables in your Flash movie based on the output of a PHP script then this is easy.
In your Flash movie you just use the load variables command and point it at the PHP script. Then, in your PHP script you do:
echo "&var1=value1&var2=value2&var3=value3";
If you want to ude PHP to act on variables within Flash then, in the same Load Vaiables command, you can send the variables within your Flash movie to the PHP script using either GET or POST methods. The variables then become available just like any other POSTed or GETed variable in PHP.
I hope this helps!