The question still remains, though: can there be a button assignment that allows one to search via a remote that doesn't have 9 buttons?

I'm not sure what you're asking here, because the Pioneer remotes have 11 buttons. Can you search using the Pioneer? Yes, but it's not incredibly intuitive due to the button layout. I've managed to set up my Hijack IR translations such that I can do it pretty reliably, but it involves the following:

1. Picking one of the buttons to be the Search button.
2. Picking a button which sends the Hijack "shift" code which toggles the definition of all of the buttons.
3. Giving the other 10 buttons the numbers 0 through 9 when they're shifted.

So to do a search, I need to hit quite a few buttons.. Search, then shift, then type in the characters to search for, then shift again to get back to the normal button definitions, then OK. I've gotten good enough at it that I can do a search for any album/track within maybe 15 seconds, though... Not too bad while still keeping one's eyes and attention on the road.