How to install gems without permission on windows

I have no permission to install gems on default Ruby system path,

I tried to downloaded all the requires gem in a folder.

How can I install those gem without permission ?

Because I require some extra gems in the script

require 'roo'
require 'writeexcel'

Thanks

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You should be able to use the Windows installer for Ruby to aim at a
directory you have write-access to and start using that installation,
although if you don’t have admin rights then the file-association in the
registry may not work.