So if I understand, you don't want data access on your Apache because you've got it on another device and want to let the Apache access the internet through that other device? I've been doing that for years...
What makes you think you need to flash it? All you have to do is... *cough* (god this is painfully obvious it hurts me to write it...) *cough*... JUST TURN IT OFF ON YOUR PLAN! Not entirely sure why that even needs to be asked
Just log into your Verizon account and, uh, switch off your data plan or switch it to "pay per KB". Then go to your connection options and remove the Cellular Line connection that dials #777 through the Cellular Line. Then you'll never get charged per KB. No flashing required... :P