I have purchased two of these kits, and it's absolutely possible to activate this online for a BYOD phone and port an existing number in. I even added this to an existing Cricket account. Here's how you do it:
1. After you receive the SIM, go to Cricketwireless.com
2a. If you already have an account, log in to your account and select "add a new line"
2b. If you have new service, go to Cricketwireless.com/join
3. Follow the prompts. When asked for you IMEI number, enter the number for the phone you are using the SIM for.
4. For ICCID, enter the number of **the SIM card that you just received. **
5. If you have done this right, it will add a BYOD SIM kit to your cart.
6. Go through the steps, including selecting a plan and entering your credit card info.
7. Complete the order. Even though it makes references to Shipping, it will be listed as "Free Shipping" 0.00 on the order summary.
8. When the order is complete, you will be given the prompt to Activate right away! Complete the activation.
9. Load up the SIM and then wait for the port in. If you've entered all the info, you should be good to go!