A tip: It is important that these cables be free moving without tight bends throughout their entire range of travel. In order for this to happen, it is important where they penetrate the firewall. IF the hole in the firewall is not lined up accurately you could have restrictions in the operation of the controls.
Install the engine on the fuselage WITHOUT the firewall. Route the controls to their best location for smooth operation where they will not interfere with anything else. Then take a measurement where they pass through the firewall location in order to drill the hole correctly. You may find you need a loop behind the firewall or on the engine side. Take into consideration whether or not you have a swing out engine mount.
In both examples which bearhawk has shown you, the ends are long requiring an unobstructed clear space. Be certain the cable does not have a sharp turn at the beginning of these ends.