I was able to successfully install of Particle-CLI (v1.8.3) on Mac OS X 10.10.5.
I did it by completely removing the most current instillation of node.js (which was v4.0.0) by following this SO guide. Then I installed node.js v0.10.27 as per this Particle forum post and now it works!
Hope this helps!
PS. My core was pre 2014 so it had a solid magenta status led color after connecting to the wifi. Once Particle-CLI was installed and I was able to perform the deep update, the core is now successfully connected to the internet and the Spark app.