So apparently you are treading on new ground here so you will have to engineer it yourself. You will need a L14-30R receptacle like this:
Which you may want to paint to match your RV color scheme if you mount it on the outside.
If you just want to put it inside a compartment then this could work:
Add some 10 gauge wire and snake it to your transfer switch and tie in where the generator input ties in. You may need to get larger wire nuts.
That should be all there is to it unless you want to add an additional inline breaker to the receptacle, but since your generator already has breakers, I don't see the point.
I may do this on my ACE just for flexibility but I only have a 4000 watt so just 120 VAC 30 Amp.