You don't need to use Intel's SDK for AppGameKit Tier 1 apps submitted through AppUp. Thanks to MSI Mini Maker it is possible to build the silent install package required by AppUp in a few steps rather than the many dozens explained in the outdated AppGameKit guide.
See:
http://forum.thegamecreators.com/?m=forum_view&t=201286&b=41 for instructions.
You'll still need a code signing certificate and Intel's
App Signing Utility to sign the EXE before uploading it.
For me getting the certificate and then going through the review process was the most tedious. Comodo required me to send them all kinds of documentation including driver's license, bank statements, phone invoices and more. Even after all of that, they still forced me to add my phone number to a random public white page directory just so they could verify my identity. Then during the review process, Intel rejected my app because I didn't include a trademark symbol after the word Ultrabook in my description.
Aside from that, I think you'll find AppUp is not very active and it's difficult to get over 100 downloads on even a free app unless you are a major publisher.
P.S., Since this is a general Tier 1 question it would've been more appropriate to post in the main AppGameKit forum--that is also a much more active forum than this one.