I have a couple of vms running CentOS 6.3 that I migrated via SRM. I had to do a number of manual steps at the end because Recovery kept saying it was waiting for vmware tools. I believe it was running but SRM didn't see it. Beyond that I had some IP customizations set up, though I've now read that IP customization will not work with CentOS. So, assuming I can get vmware tools issue fixed, can I run post-SRM scripts to customize the IP address? I assume they have to be run as root
Customization of CentOS is not currently supported indeed.
If you are using SRM 5.0 or 5.1, then both script execution and IP customization use the same method, So, running custom scripts to change IP may not work as well.
Regarding VMware Tools timeout, is your VMTools up-to-date?