Here is some JavaScript that should achieve your requirements. Just change the field names to match the ones in your custom form. You can wire this function to the onload and onchange event of the owner and requester fields.
Hope this helps.
function requesterCheck() {
var owner = Xrm.Page.getAttribute("ownerid");
var requester = Xrm.Page.getAttribute("new_requesterid");
if (owner.getValue() != null && requester.getValue() != null) { // Check that Owner and Requester have a Value
if (owner.getValue()[0].id === requester.getValue()[0].id) // Then compare if they have the same GUID
Xrm.Page.ui.controls.get("new_requesterstatus").setDisabled(true); // Disable the Requester Status field if same
else
Xrm.Page.ui.controls.get("new_requesterstatus").setDisabled(false); // else enable the Requester Status field
}
}
Eric UNG [Senior Analyst Programmer :: Sydney, Australia]