first this should be in the modding questions thread... the scriptorium is for tutorials

and to have the moors and white huns requires a lot of modding... first you need to consider which faction to replace (since there is a 20 faction +rebel limit) then you have to alter the unit files and the textures and models files and the descr_sm_factions and of cousre expanded.txt
i would like to be more specific but since i haven't actually done it myself i will leave it to someone who has... but since it is a lot of work i suggest you make a backup copy of your BI folder so as you can still play while you are editing

hope i could help
GMM