How can I record multiple premiums for a contribution?
Perhaps this can be achieved through the use of price sets and multiple contribution pages, e.g.:


Main contribution page can be the lowest level premium option with links to the higher levels of sponsorships, each level is its own contribution page
(e.g. main page = Sticker Level, linked page = T-Shirt Level, etc.) 
The price set for the sticker level would only include the sticker option at whatever the amount it is that you are requesting as required
The price set for the t-shirt level would include the option to select to receive a sticker with a price of $0, and then the t-shirt level amount that is required


Hope this helps!