Here's the format of the .eqitem file that PacketCollector makes. v0.2 will hopefully have some ability to upload packets to a central database, but this file will still be made so you can always use your own items for whatever you please.
	Code:
	#define MAXITEMID 33000
/*
  Struct that defines the file format used to store the items.
  The index of the "index" array is the ItemID#, the value is the index of the "items"
  array that holds that item, or 0xFFFF if the item isnt in the file.
*/
#pragma pack(1)
struct ItemFile_Format {
	int16		index[MAXITEMID];
	Item_Struct	items[0];
};
#pragma pack()