I am not sure about importing off the web but it might be possible to use your printscreen button. Then use a photo shop program to change the picture you create to an image that OZI use's.
The best method I have found to get around the expensive digital chart is to buy the paper chart you want then run down to kinkos and have then scan the chart and put it on CD for you then you can manipulate the image however you need to. I am not real familar with Ozi explore but a friend of mine has it and he is the one the changes the image to be calibrated. Hope that helps.