Change the background
Add the linkbar (computer needed)
Revert to defaults
To add the linkbar, connect your PSP to your computer.
Next, go to the "common" folder, on your PSP. Now, rename either the "linkbar.html", or "custom homepage and linkbar.html" to "BG". (You may need to re-download The Homepage Portal to get these files. You may download it right here.)
Now, drag the document you just renamed, to the "Homepage" folder.
To refer to defaults, re-download The Homepage Portal, from here.