You may be able to convert the vCard to CSV, in which case the data will be able to be imported - Act! can import any data from a CSV. I know it's possible to do this by importing the vCard into Outlook, then exporting the contacts from Outlook to a csv file - but there's likely easier ways available on the web - some form of VCF to CSV converter.
So, unfortunately, it's not a process that Act supports, but may be possible with the use of third party software. If you can get the data into a CSV format, then we can help with the import process.