on desktop you can't put launcher. elementary does't support "have file manager handle desktop"
in dock (plank), open the app and his launcher is been show in dock. right click on icon and in meny go to "keep to dock".
in wingpanel, same as unity panel, is possibe via dconf-editor some, but launcher to panel not. indicators in panel & message meny work like in unity panel
I've managed to install elementary desktop by rebuilding ubuntu-extras-keyring locally on my system, like this:
mkdir somedir; cd somedir
sudo apt-get install -y debhelper
wget http://archive.ubuntu.com/ubuntu/pool/main/u/ubuntu-extras-keyring/ubuntu-extras-keyring_2010.09.27.{tar.gz,dsc}
tar -xf *.tar.gz
cd ubuntu-extras-keyring-2010.09.17
debuild -i -us -uc -b
sudo dpkg -i ../ubuntu-extras-keyring_2010.09.27_all.deb
After that, elementary-desktop will install, but will error out at the end because it depends on systemd-shim which is no longer needed nor wanted with 15.04 having a full SystemD implementation.
When it errors out, run
sudo dpkg --force-depends -r indicator-datetime
sudo apt-get purge unity-control-center unity-control-center-signon
and it should complete the installation.
I expect in the near future the Elementary folks will fix their repository to handle SystemD properly - Ubuntu 15.04 move to SystemD was done a few weeks before the official release and the Elementary guys probably didn't have time to adapt to that.
After installation, you can log out and see "Pantheon" in your display manager's session list, but if you try to log in you'd get just the blueprint paper styled Elementary "beta wallpaper". The problem is that the session starts Slingshot and Gala, but not WingPanel or Plank. Currently I'm using using Slingshot's ALT-F2 shortcut to open the launcher and run Plank and WingPanel manually (just type the name in all lowercase and hit ENTER).
Best Answer
This is answer for newer releases of Ubuntu — 12.04 and up. Remember, use this at your own risk!
Open a terminal (Ctrl+Alt+T).
Add the repositories and update the package list:
Upgrade your packages...
...and install:
After completed installation log out and chose session called Pantheon in LightDM.