Modify LTM vserver VS Score with an iRule?

I have two sites and an LTM in each site. I'm balancing between the sites using a BIG-IP DNS (GTM) wideIP & GSLB pool using the VS Score Load Balancing Method. I can observe the desired behavior by manually setting a VS Score value for my vservers in one of the sites, but I want to set the VS Score value dynamically using an iRule on the LTM. Is this possible?