Building and using spidermonkey (or v8) - is there a detailed working tutorial?

Question

JavaScript

Good afternoon (morning, evening, night)!
Have you ever collected spidermonkey? I would love to get advice from you about its assembly.
I followed these docs:
https://developer.mozilla.org/en-US/docs/Mozilla/P...
https://developer.mozilla.org/en-US/docs/Mozilla/P...
But it looks like the hands still somehow grow incorrectly :(
Of course, I can give all my actions (which, I believe, are fully consistent with the instructions above) and their results.
Maybe I'm stupid on something obvious. I'm
also interested in building and using V8, like alternative ( in case you can help with this I will also be grateful )
Thank you for your attention.