I finally got it figured out. Issues were part novice on my part plus a piece of bad sccript provided by support (not casting stones, I'm human too).
For anyone that might be having similar problems, here's the sccript I used:
<sccript type="text/javasccript"><![CDATA[
function MinDonation()
{
var obj = __EFGetElementByEFFieldName('datDonation');
if (obj.value < 50)
obj.value = 50;
__doPostBack(null, null);
}
//]]></sccript>
For the benefit of anyone trying to figure out scipting, here's some notes:
1) the sccript was put into an HTML field in the form. In the Fck (or whatever it is) editor, it's "invisible" - click on the "source" button to see/edit it.
2) the sccript is called from a client action using "return MinDonation()"
3) the sccript checks the value of field "datDonation". If less than 50, it resets the value to 50. Needs an error message when this happens, but not present in this version.
4) the [CDATA[ and ]] stuff (supposedly) makes this XHTML compliant. Needed? I don't know, but it works.
Hope this helps someone else!
Steve