I found a couple older threads but I couldn't find any existing add-on for this or where this might be in configuration.
Is it possible with any existing gateway to capture payment when an order is shipped or only at the time of checkout?
For example in the included Authorize AIM method, it can be configured to "Authorize Only", but the documentation doesn't show how you would then go about capturing that payment.
Is this possible with simtech's CIM addon, or does that just let customers save credit cards in their profile?
If you do not find ready to use module, usually capture action can be made from the payment system dashboard.
This is payment provider specific. We have done an AIM "pay capture" module to accomplish this. Please contact us for info about it. We don't offer it as a production addon since it requires the insertion of one hook in the payment module.
Essentially it enables you to "capture" at any point in the process. You can also void, refund and make additional charges against the card (but that feature requires that you retain the card which in today's world is not advised). It is only integrated with AIM and not CIM modules.
Feel free to contact us and we can provide you an addon that will insert the required hook and enable the functionality.
Am I right in saying the paypal addon does still not do this yet paypal does support it?
Yes, PayPal addon still does not support it