| Grummik |
Here are the rules that govern Wondrous Items in the corebook.
"Special Qualities: Roll d%. An 01 result indicates the wondrous item is intelligent, 02–31 indicates that something (a design, inscription, or the like) provides a clue to its function, and 32–100 indicates no special qualities. Intelligent items have extra abilities and sometimes extraordinary powers and special purposes (see Intelligent Items).
Wondrous items with charges can never be intelligent."
Also, when reading the intelligent items section there is nothing with a ghost touch ability that I can see.
I would say no, you should not be able to add ghost touch to a wondrous item per RAW. If you were to allow that it would be house rule/homebrew specific.
My .02