you sure can make a macro with an item link in it, but the skulls and other emotes are not possible like ohr said.
http://wowwiki.wikia.com/API_SendChatMessagethat's the function you will need to send a yell via macro
and here is an example how itemlinks in macros look like
/script DEFAULT_CHAT_FRAME:AddMessage("\124cffff8000\124Hitem:17182:0:0:0:0:0:0:0:0:0:0\124h[Sulfuras, Hand of Ragnaros]\124h\124r");
but there is another thing which will make problems, if I'm not mistaken the only channels where you are technically allowed to link items are trade chat/party/say/guild/whisper chats. if you link an item in other channels they will see the itemlink like it's in the macro I posted IF THEY don't have an addon which converts it all pervectly which not all have.
/run SendChatMessage("\124cffff8000\124Hitem:17182:0:0:0:0:0:0:0:0:0:0\124h[Sulfuras, Hand of Ragnaros]\124h\124r","YELL")
would be an example how to use it (here again an reminder: I'm pretty sure yell shouldn't allow to link itemlinks which means it will not "link" the item correctly in this channel for players without a proper addon but that is how it would work - it worked in my UI)
to get the itemlink in the format of my example visist eg. wowhead search your item and click on Links, there is such a chat itemlink for every item