I don't think this really belongs in this forum lol. This forum is more for asking questions about the site.. though I'm not really sure where this would be fitting considering there isn't really any subforum just to chat about the stickers o3o;
If you're asking if you're allowed to have someone lend you the item for the sake of the sticker, yes, you are allowed to borrow items, but both you and anyone involved should be careful about the potential for scams, since any agreement is never 100% safe. 'v'
Otherwise, if you'd like to specifically ask others for these kinds of arrangements, they can be done in the Babblesphere in a casual manner; be tactful as begging will likely not be looked upon favorably. n__n