I personally have my contacts in a PHP/MySQL app I coded. I can export them as a set of txt files, one per contact and I find this enough (if not great) to read the contact info with the Rockbox txt viewer.
1) You could try the Lua plugin to code an app for parsing and displaying the contacts and then their info,
2) or find (or code) a script that will create the set txt files from the csv file on your computer, then copy them to your player. This should be at most ten lines of Python, not counting the txt template.