Prototype CSS selector to descend tree?

Hi, I’m calling on those with Prototype/CSS selector foo to help with a
somewhat tricky issue.

I have a tree structure where each item is hierarchical. This is used
to manage software components. Think of the case where you’re
installing a piece of software, and want to customize which packages
are installed:

[ ] Internet
[ ] Email
[ ] Thunderbird
[ ] Evolution
[ ] Outlook Express
[ ] Browsing
[ ] Firefox
[ ] Internet Explorer
[ ] Entertainment
[ ] Music
[ ] iTunes
[ ] Winamp

In this menu, if the user clicks on a given checkbox, I want all sub
elements to check as well (and the same on uncheck, obviously).

Since there are all simple checkboxes, I tried attaching this function
to onclick:

function toggle_children (input) {
// locate “input#myid input” (all children)
$$(‘input#’+input.id+’ input’).each(function (item) {
if (input.id !== item.id) {
item.checked = input.checked;
}
});
}

But unfortunately, that did not select the elements. The pure CSS
selector that should work is:

input#myid > input

However, unfortunately passing that to Prototype gives "error parsing
selector at: > "

Ideas?

Thanks,
Nate

Just to be sure, can you post your ®html here?