So I have fully created my entity, texture, AI, everything's working perfectly. However my spawn egg is in the miscellaneous tab and I cant seem to change it. Where would I put the setCreativeTab()?

I guess you have to add it as a "Sub Item Thingie" as you would for example add custom Wool:

When you have actually created a SubItem in the Process of making your mod you could just add this to the Item class:

    @Override
    public void getSubItems(Item item, CreativeTabs tab, List subItems) {
        ItemStack is = new ItemStack(All the Information nessesary for the Spawn egg); //You might have to add NBT Data to the stack...
        subItem.add(is);
    }

Cool it worked thanks.