changing values deep in an array by reference, with some index vars in array..

Hi..

I've got a db-insert command array that's several levels deep..
Let's abstract this as:
$wm[$idx1][$idx2][$idx3][..etc] //$WorkMemory

Several of my helper functions need to work on the "original,
top-call_level" $wm.
So i pass it as &$wm, and have the helper function declarations accept
it as such aswell.

Some of the $idxN vars are in an array $pathToDBcmd ($idx3, $idx4,
...) in some of the helper functions.

Now i need to change a variable deep in the original, top-call_level
$wm, but with some of the required indexes in $pathToDBcmd..

I can't use something like
$wm[$idx1][$idx2][$pathToDBcmd[0]][$pathToDBcmd[1]] because i dont
know what count($pathToDBcmd) is..

Tips will be much appreciated..