I do a batch of powder coating several times a week, hundreds of batches over the years.
You will need to disassemble everything, remove springs and plastic, plug and cap threads.  The parts being coated will be in an oven for about 20 minutes at 400 degrees Fahrenheit.  If its for exterior parts being exposed to sunlight the top coat will need to be polyester powder to resist UV degradation.  Interior parts can be epoxy.  

If you think the springs in the lifting mechanism in the pop top can withstand the oven heat, then you may be able to leave it together.  
If you were local to me I’d do it for you.  

Gary Lee
www.vwrack.com

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I was thinking about having my table legs powder coated in silver because
of the bits of corrosion and nicks that have accumulated on them over the
years. While I'm at it, I would like to powder coat the spring-loaded top
raising mechanism. Will this be possible without taking the thing apart?
From my dealings with these things loose out of the car, dealing with them
is like trying to fight an ostritch. I would not want to take one apart.