Can you rename the TS cookie used with ASM?

ASM does not have the ability to rename the built-in TS cookies.

Why do you want to do it? To hide that you are using ASM? This is only a "security by obscurity" and will not make more secure. Attackers can always fingerprint BIG-IPs and figure out that you have ASM protection based on getting a blocking page response on some generic signature.

I doubt that PCI-DSS will give you any trouble for the fact that you can prove that you have a WAF :) on more serious note though what the auditors would look for is patching level. There have been several security vulnerabilities in F5 products in the past few months, so make sure you have the latest Hotfixes.

Here is a handy link listing all F5 vulnerabilities (CVEs) in 2016:

F5 CVE Details