Assigning an IP to a specific instance.

[Travis]

Is there a way with a script to assign a specific IP address to an
instance, just like if you chose options on the instances page, and
then assigned an elastic IP address? I understand how to do this with
the Amazon ec2 tools, but I don't know how to get Scalr to register
the updated IP address to the DNS servers.

Once an IP address has been assigned to a role, is there a way to
disassociate that IP from a role, so it can be re-assigned? I have an
IP address that I'd like to keep but it's stuck in a state where I
can't assign it to another instance in Scalr, because it's associated
with a role.

Thanks.