All I Want is tuned F#G#G#G#
Carey is tuned DDAA
Case Of You DAAE (though I play a version GDAE ie a mandolin tuning which works fine)

Most of them are on the site Peter pointed out and easily adapted

I have an old guitar that has 4 strings on it that I tune to the above and accompany my wife when she sings Joni songs. Works fine. Usually with lots of laughs from people when I bring it out as it looks pretty battered and weird and like a guitar with two missing strings!

Haven't tried California but there is a tab for it on that site which looks right