No way to hook into the config

I am still having an issue finding a way to hook into the config.
Does anyone know how to programmatically set a config setting.
ie. pgcache.memcache.servers

I found this hook “w3tc_save_options”, but it will only run when saving the options.

I am hoping for a define() that I can put into the wp-config.php

ie.
define(‘WP_CONFIG_pgcache.memcache.servers’, ‘1.1.1.1:11211,2.2.2.2:11211’);

Our Memcacher Server IP will change periodically due to power outages or reboots and will get a new IP assigned to it. I am able to get the current IP with php.

Thanks