If the file is ASCII format, there is an example in LabVIEW Example Finder to show you how to read from this file called Read from Test File.vi. The Example Finder is located under Help » Find Examples...
After this you will have the vectors so you can send these out your card. For examples how to use your PXI-6552, they can be found in the LabVIEW Example Finder under Hardware Input And Ouput » Modular Instruments » NI-HSDIO.
There is a better way to import these .vcd vectors into LabVIEW for you to use. We have a program called Digital Waveform Editor allow you to import test vectors from VCD or ASCII files from VHDL design simulation packages. You can find this program under Start » Programs » National Instruments » Digital Waveform Editor.
If you have this program installed, here are the steps in order to import this file into it:
1.) Navigate to File » Import » From VCD...
2.) The VCD Import Wizard will open. Select the VCD file to open.
3.) For Steps for how to complete the VCD Import Wizard, open the Digital Waveform Editor's help and search for VCD Import Wizard. It explains all the details of the Wizards and possible caveats you might run into.
4.) After completing these steps, select the Generate Waveform button to create a .hws file from this that can be imported into LabVIEW.
I found in the LabVIEW Example Finder called Stimulus Response Load from HWS file.vi. I am sorry about this initial confusion and I hope this information helps you.