One way of doing it is by use of the "PM" feature. Basically, it's like swapping radios from one to another. It won't allow you do 'do' scanning in one 'PM' and talking in another 'PM' at the same time though.
I'd also add my recommendation for that 'user group', I think someone there has made all the 'mistakes' before so that you don't have to.
(Don't expect me to answer the 'how to' with that 'PM' thingy, I don't know.