A PE4H ver2.4 with EC2C is an ExpressCard setup. The PCI express you are talking about is either a PE4H ver2.4 with HP1A (1x addon) or a PE4H ver2.4 with HP4A (4x addon). So the EC2C is what you need indeed.
You still need a PCIe Video Card (PCIe 1.0, 2.0, or 2.1) and an external display.
However: PCIe add-on cards are designed for desktops. Compatibility with your laptop is not guaranteed, it depends on OS version, notebook’s BIOS and device driver. Most PCIe 16x video cards cannot get enough memory resource allocated and therefore the question is if it will work with your laptop.