Hi sportflyer,
Yes, this is easy to accomplish by using a Pmix to deactivate the switch.
Please check our FAQ's for this radio at:
http://www.futaba-rc.com/faq/faq-8u.html
This one particularly will help you out:
http://www.futaba-rc.com/faq/faq-8u-q52.html
I hope you find this information helpful. You can also reach our Futaba support technical team at 217-398-8970, or via fax at 217-398-7721.
Sincerely,
Krysta
Lead Futaba Customer Service and Programming Technician