I'd say Section by section,
many, many, many years ago I learnt the bass solo section (5X12 bars) first,
12 bars at the time...
Afterward, I learned the beginning, then the end section,.
It did take a while...maybe two weeks for the solo section,
then probably another week for the rest.
Here is a close-up video of my left hand, playing along the real solo
it might help
You Play Along! - Lemon Song - John Paul Jones Bass Solo
Oh yeah, here is cover version, a re-recording of the "Lemon Song" that I had the chance to work on, that was done for a "music-minus-one" company back in the mid 90's.
Lemon Song - Led Zeppelin sound-alike by ericbeaule on SoundCloud - Create, record and share your sounds for free
Hope this helps
With work and dedication you can do it