Simply put---no. Digital Recorders which use flash memory can only use their specified media. I can't be sure about the DP02, but in the case of the two Boss BR decks that my wife and I own but the only media they will accept are 1GB CF cards, and not CF II Ultra or multiple gig cards. Find a good source, because CF cards are no longer being made.
Your, operating system on the DP02 won't recognize an external hard drive as recording media. Even if the os could do so, the usb port is only set up as a transfer interface. Now if there were an adapter similar to the old cd to cassette type, where you have a cf card wired up to a usb cable, then you might have something. But then your next obstacle is how much of that hd is the os on the recorder going to recognize? If it only uses 1GB, then you've wasted a lot of effort.
Call Tascam support and find out how large and what speed CF card you can use, then go buy as many as you can find.
Your other options are to record to a computer-based DAW (defeats the point of being portable) or record on the deck then record into the DAW, usb drag and drop, or plug your recorder-formatted CF card into the card reader and still drag and drop.