You can use a workaround:
add server, Profile name: <paused>, Hostname: 127.0.0.1, Maximum allowed connections: 0
Open the NZB with this server. Select the files you want and select "Download with other server".
Select the server used for downloading.
This can also be used to keep the par2 in the list so you can download them only if you need them.
Newsleecher can auto pause files (filetype and/or filename) if they are listed in a filter.