I have upgraded the LVM collector in my StorageCollector repository on github (https://github.com/charlesnagy/Diamond-StorageCollectors) to match the new directory structure of Diamond and added support to collect flashcache metrics.
Move the flashcache directory to your collectors directory which should exist on /usr/local/share/diamond/collectors or /usr/share/diamond/collectors path depending on your installation.
Configuration is straightforward:
In the /etc/diamond/collectors directory create a file called FlashcacheCollector with the following content:
enabled = True
Of course you can specify all the usual stuff for diamond like path, interval etc.