I dont think there's a tutorial on this.
The only file you should need to change is Civ4UnitInfos.xml
There is a block of code for every unit. The file is long, so use search funktion... for example if you look for "carrier" you will find
<SpecialCargo>SPECIALUNIT_FIGHTER</SpecialCargo>
<DomainCargo>DOMAIN_AIR</DomainCargo>
<iCargo>3</iCargo>
In the corresponding block. That makes a carries carry fighters. Wherear a Transport looks like this:
<SpecialCargo>NONE</SpecialCargo>
<DomainCargo>DOMAIN_LAND</DomainCargo>
<iCargo>4</iCargo>
and will carry all land units...
You can look up in the same file, in a block of any unit, what domain that unit belongs to and waht kind of specialunit (if any) it is.