You are storing them on a SD card presumbly(?), you don't use desktop manager, just plug in as mass storage mode. drag and drop the .jad AND corresponding .cod files to the sd card.
Then search the sd card for those files, click the jad file and it will ask to install it.
Themes are not viewable until they are installed.
"That's it then. Cancel the kitchen scraps for lepers and orphans, no more merciful beheadings... and call off Christmas."