In general the process for converting a theme does just involve getting the content to show up in the right spots in the theme. There's some info about theme creation in the documentation: overview & output functions.
When converting a theme, you might also run into some differences within the CSS styles. The menus for gpEasy use a <UL><LI><A> structure that many designers have planned for.
Sorry for not getting back earlier, I lost track of this one.
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