Trouble with Installing Spotty

Hi,
I suspect that this has been posted before so apologies for taking up your time.
After having used a Squeezebox touch, LMS server, squeezeslave and iPeng for a couple of years, I am currently trying to use Spotify in this environment.
Unfortunately, the Spotify plugin does not seem to work, and I am unsure about how to install the Spotty plugin. On my LMS, I cannot even see 3rd party plugins as a separate option in Settings.

Here's the info about my system:

1. MacBook Air running OS X 10.7.5. Since it is a very old laptop, I would prefer to not have to install a newer OS
2. LMS 7.7.5
3. SB Touch 7.7.3-r6676

Any help would be great.

Thanks so much
Daniel