First buy keyclone.

Then set it up so you have added both wow accounts to the keyclone.

Go to the key commands and click white list and white list keys 1 2 3 and q e and f

On your priest make a macro that will heal your hunter and bind it to q then make a macro for shield bind it to f and renew bind it to e.

on buttons 1 2 and 3 for both characters set up your dps spells

So on the priest button 1 would be your dot for shadow word pain and on your hunter it would be serp sting

button 2 would be steady shot for the hunter and mind blast for the priest and button 3 would be mind flay and either con shot or something else.

this is the setup I use.