Two ways, use either one.
1) Shebang. The shebang goes on the very file line of the script and tells the system which binary to use in running the script. It's more commonly used in shell scripting, but can also be used with php. So, in your case, the script would start like this:
#!/usr/bin/php
<?php
/*
* Rest of script
*/
Then in the cron setup, you'd just reference the script's full location.
/home/Dolemite/www/cron/thisfile.php
2) Point the binary to the script in the cron setup. Like above, except without the shebang, and the line in the cron setup would be
/usr/bin/php /home/Dolemite/www/cron/thisfile.php