You can either call them by specifying the interpreter to load the scripts in the crontab, with this syntax:
* * * * * /usr/php/54/usr/bin/php yourscript.php
Or, alternatively, if you are comfortable modifying the scripts, you can use a shebang line on top of it. To use the shebang line you just need to modify the first line of the script to look like this:
Then you need to make the script executable with
chmod +x yourscript.php and then you can directly call it without specifying the interpreter like:
* * * * * yourscript.php
Here is more documentation about the shebang line: shebang
In many cases I think probably the first way (specifying the interpreter in the crontab) would be preferred, because it doesn't require you to modify the script itself.