If the link is enabled for the clients on AccessPoint, and the end user has installed the IE plugin, it can be selected when you press "View details" of a document beneath the name and the thumbnail. If not visible (only works in IE), then you need to allow it, usually there is a yellow bar or a popup from Internet Explorer asking you to confirm it to run.
You can set it to be the default client inside the QMC, on the same settings page as where you enable the download link. It can also be selected as the preferred client for the individual user by clicking "Favorites & Profile" > "Profile" on the AccessPoint upper right corner.
as Control Panel shows, I have QvPluginSetup (size 76,3MB) installed, version 11.20.11718.0.
When I click 'view details', I do not see IE plugin as an option - IE neither prompts me to confirm it to run.
I would rather not make it the default client - only allow it for a certain user who needs to use this macro creating Excels, so 'make it possible' would be an adequate setting.