"_ADD_ITEM_EXTERN" is a Stored Procedure of SRO_VT_SHARD, you can use it within the SP of _AddNewChar to add like you stated a Dress as a startup item e.g.
PHP Code:
exec _ADD_ITEM_EXTERN Caipi,'ITEM_EVENT_AVATAR_M_CH_WEDDING_HAT',1,1
Caipi = Char Nickname
ITEM_EVENT_AVATAR_M_CH_WEDDING_HAT = Spawncode
1 = Quantity e.g. 50 for like 50 Potions
1 = +value e.g. for an Item use '12' and it'll appear as +12 in your inventory