HOWTO:Get started working with Lily source code
From LilyWiki
Here are the steps to get and install the Lily source code. Note that you only need to follow these steps if you want to work on (as opposed to with) the Lily application itself. If you just want to use Lily, then simply download it and install the .xpi file using this guide.
1) Uninstall Lily if you've previously installed the XPI.
2) Install a [subversion] client if you don't have one already. There are many clients out there- here's what I've used and can recommend: Windows [TortoiseSVN], Mac [Martin Ott], Ubuntu Linux "sudo apt-get install subversion"
3) Once subversion is installed, create a folder somewhere convenient where you'd like your code to live. Name it whatever you like. If you have a command line subversion client, cd to that folder and run the command: "svn co svn checkout http://lilyapp.googlecode.com/svn/trunk/ lily". If you're using TortiseSVN, right click on the folder, select "SVN checkout" and enter "http://lilyapp.googlecode.com/svn/trunk/" as the repository url. If all goes well, this should download the latest version of the source code to this folder.
4) Now that you have the code, you have to install it in Firefox. First find your firefox profile folder- http://kb.mozillazine.org/Profile_folder.
5) Create a text file in your_profile_directory/extensions/ with the filename- "{3eba6510-7445-11db-9fe1-0800200c9a66}". There's an example of this file in the Lily source code located at <your_checkout_folder>/lily/{3eba6510-7445-11db-9fe1-0800200c9a66}. If you want, you can just copy this file to the extensions directory in your profile folder.
6) Open the text file and enter the full path to the folder in your Lily checkout where install.rdf is located. Assuming you're working on the trunk, then this will be at your_checkout_folder/lily/lily (eg. `/full/path/to/your_checkout_folder/lily/lily`. Windows users should use the drive name (CAPS) and backslashes instead of slashes: eg. `C:\full\path\to\your_checkout_folder\trunk\lily\lily`).
7) Restart firefox- you should see Lily in the "Tools" menu.
8) Note that you'll have to restart firefox to see any changes you make to the code.
9) Additional info here- http://developer.mozilla.org/en/docs/Setting_up_extension_development_environment.
