This is how I do it and keep all my old or personal objects, skies, and materials I have collected over the years.

Create a folder and name it appropiately and save it anywhere you can find it again. Go to the Bryce folder on your system and open it, go to the presets folder in there and copy the "objects" in it  to the new folder you just created and paste it there. You can do the same for the skies and materials as well.

When you install the new Bryce, just copy the contents of your new folder into the "objects" folder in the new presets folder created by the installation - BTW, it is always a good idea to keep copies of all those things somewhere else , especially burnt to a disk in case there is some sort of program malfunction or corruption of the original files. Then you will always have them to reload back into any reinstallation of Bryce.