For a 4 wire line for a dryer, how do I connect the neutral and ground wires into a breaker panel that has a common ground and neutral bus?
If this panel is a real main breaker panel then the netural and ground is there on the common netural / ground bussbar but just make sure you only use one hole per netural but the ground can be bundled up.
That part I rather run it own due the conductor size.
But if your panel do have seperated ground bussbar then seperate them and hook them up in proper place et it is not very hard to find them in the panel.
The neutal bussbar will have a bit of white conductors go on that bussbar ( sure there will be bare or green but once you have subpanel then the bet is out of the window. )
The answer will be based on NEC ( National Electrical code ) or CEC ( Cananda Electrical code ) or ECF ( Electrique Code France )