From OLPC

[edit] WARNING

Adobe Flash has a proprietary license which prevents redistribution. It will be in violation of the license to distribute your resultant build unless you have received special permission from Adobe.

You can request such permission on the Adobe website.

[edit] Add it

Just add adobe_flash to the modules list.

While Flash is available as a standard Fedora RPM distributed by Adobe, it breaks the rules of packaging. This means that it requires speciall support from this module.