How to make a girly theme party appeal to boys?

Personally, I'd have them dress up as the dwarves... They were more centrally featured in the story... Maybe buy tee-shirts, batting to stuff them plump, some belts, mining tools to hang from the belts, etc. (I'd probably go the easy route and ask the parents to outfit their kids as dwarves and maids/princesses...) I do think a mining game is needed. You could spray paint some blocks or rocks w/metallic gold paint, have all the kids mine (even the snow-whites... perhaps as part of a team...) Give out ring-pops to the team who mines the most gold...

The prince actually did very little in this story. He sang to Snow White at the beginning and then didn't show up again until the end - where he kissed Snow White. Considering the children's ages, I would prefer not to re-enact the prince's role.