What am I missing here? MBP 9,2

I’m getting ready to attempt to update my MBP using OCLP. Read the website a bunch, and watched some videos and process seems pretty straight forward, except one seemingly obvious question, that all my searching doesn’t seem to yield a direct answer to.

MBP 9,2 a1278… 8gb DDR3 Ram, 2.5 GHz i5, 500 GB SATA Disc.

Currently running OS X 10.9.5 which appears to be newest Apple will allow to DL, however OCLP requires 10.10 … so the question is how do I update this thing when the machine is too old to run the application?

OLCP clearly states they support updates to machines all the way back to 2007 which obviously would have even older OS… what step am I missing in all this documentation that allows you to run this process with OS older than 10.10?

I’m sure the answer is obvious and I’m just missing something lol