I'll write something up right now.
In the mean time, check this out.
Edit:
Simba Code:
program new;
{$include SRL/SRL.scar}
var
Item : TInvenItem;
begin
SetupSRL;
Item := GetInven(1);
Writeln(Format('Item Slot: %d', [1]));
Writeln('ExistsItem: ' + ToStr(Item.ExistsItem));
if not Item.ExistsItem then
exit;
Writeln(Format('Width: %d, Height: %d', [Item.Width, Item.Height]));
Writeln(Format('ItemBox: (x1=%d,y1=%d,x2=%d,y2=%d)', [Item.ItemBox.x1, Item.ItemBox.y1, Item.ItemBox.x2, Item.ItemBox.y2]));
Writeln(Format('CenterPoint: (%d, %d)', [Item.CenterPoint.x, Item.CenterPoint.y]));
end.
TInvenItem is a record.