Hi,
I think the only thing that does not work any more with eCATT is assigning roles. This got broken when SAP switched to new screens that use component that is not supported by eCATT. If you need to do this as well then already mentioned LSMW that can use BAPI will allow you to create the users. I guess the main question is why you have to do this? Why there is no identity management system in place that will do it automatically for you. Not that you can quickly change it.
Cheers