The "Package files..." setting cannot send codes for any other products, so you'd need to enable the Send Stored Codes setting for the bundle product and, as you suggested, supply each line in the stored codes box with a serial for each product in the bundle, e.g.:
[Product 1 serial]: xxxx-xxxx & [product 2 serial]: xxxx-xxxx & etc...
[Product 1 serial]: yyyy-yyyy & [product 2 serial]: yyyy-yyyy & etc...
[Product 1 serial]: zzzz-zzzz & [product 2 serial]: zzzz-zzzz & etc...
Note that, despite however long lines might "wrap" in the stored codes box, only a "hard return" counts as an end-of-line. Also, you will want to paste your codes in from a PC or Linux browser, as there's a known issue with Adobe's Flash player plugin for the Mac that causes it to discard all newline characters in pasted text.