Let me ask chatgpt for you

)
To perform a POST request using Python's mechanize, you can follow these steps:
Import the necessary modules.
Create an instance of mechanize.Browser.
Prepare the data you want to send in the POST request.
Use the open() method of the Browser instance to send the POST request.
Here's an example based on the information provided in the sources:
import mechanize
import urllib.parse
# Create a browser instance
browser = mechanize.Browser()
# Define the URL for the POST request
post_url = 'http://example.com/login.php'
# Prepare the data to be sent
parameters = {
"username": "avi",
"password": "stackoverflow"
}
# Encode the data
encoded_data = urllib.parse.urlencode(parameters)
# Send the POST request
response = browser.open(post_url, data=encoded_data)
# Read and print the response content
print(response.read())
Though really, all due respect (which is not much) to chatgpt, the correct way to make post requests is to create a mechanize Request object with method="POST". See for example hbr.recipe in calibre's sources.
And you dont need to trick requests into anything. Store its whl file in your plugin zip file, extract it to filesystem and import from there.