Take Command

Take Command enhances the External Command Seat so you can now assign crew to it from within the VAB/SPH just like any other command module.  Just add one or more command seats to your ship, assign crew as usual, and launch!  Your Kerbal crew will automatically spawn and jump into their assigned seats.

Credits

– TouhouTorpedo for giving me idea.  Unfortunately his SeatFixer mod is no longer available so I've done my best to recreate it based on the original description.

– Nifty255 for his great assortment of YouTube modding tutorials.

– Sarbian for ModuleManager

– Everyone in the KSP development forums who have posted helpful links and code samples.