I'm afraid not - those are the only two add-ons we released, and the other two add-on dictionaries we offer for PlecoDict are too big to use with Oxford.
The flashcards should work as long as you're not using one of the newer Palm models (the ones with flash memory or a hard drive instead of RAM for storage, i.e. the Treo 650, Tungsten T5, TX, E2, LifeDrive, and I think Z22). You can export the flashcards later using the Oxford Flashcard Converter utility (available at http://www.pleco.com/oxforddownload.html).
Sorry, when I was talking about flashcards I meant the flashcard software, not the premade flashcard lists. Those only work with PlecoDict. But PlecoDict Basic is a free upgrade, so assuming your Palm supports it you might as well just install that - download the PlecoDict installer from http://www.pleco.com/palmdownload.html and your keyfile from http://www.pleco.com/orders.html, install both of those, run "PDUnlock" on your Palm and that will give you your free upgrade copy.
Does your Palm have a memory expansion card slot? What type of Palm is this? How much free memory does it have? (you can check that in the "Info" screen, accessible in the "App" menu in the application launcher)
Assuming it's running Palm OS OS 4.0 or later, it should be possible to install a stripped-down version of PlecoDict with handwriting recognition - I can tell you for certain once I know what type of Palm it is.