Dynamic readonly via javascript in spreadsheet mode

Hello,

Is it posible to make a field readonly via a javascript onload event when the list page is in spreadsheet mode? In an older version of ASPR this was my code:

Edit page - Process record values

if (values["EDI"])
{
pageObject.setProxyValue("edi", 1);
}

Edit page - JavaScript OnLoad event

if (proxy["edi"])
{
var q = Runner.getControl(pageid,'Quantity');

}

This doesn't seem to work in ASPR 10.5 when the list page is in spreadsheet mode. I even tried to remove the "if proxy" bit and just make all feilds readonly but that didn't work either. Is this still possible in spreadsheet mode?

Thanks,
Tim