Hi,
The waitlist is a notification system, when the email is send to the customer to tell him that the product is know in stock, his email is removed from the list.
And a customer without account could subscribe to the notification just with his email.
These two points make me think that it is not possible to use the waitlist for your request. It is a different feature.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.