Ubercart

//here the call, that should be done some time later (and repeatedly)
$(document).ready(function() {
//note that "cash", "bank-transfer" and "cod" are hardcoded payment method names
    var cash = document.getElementById('edit-panes-payment-payment-method-cash');
    var bank = document.getElementById('edit-panes-payment-payment-method-bank-transfer');
    var cod  = document.getElementById('edit-panes-payment-payment-method-cod');

//this div _will_ contain the shipping radio-buttons
    var quoteDiv = document.getElementById('quote');
    if (quoteDiv == null) return;

//problem: on $(document).ready this <div> is empty - filled later. And updated... so this all must be executed on update of shipping methods.

    var inputs = quoteDiv.getElementsByTagName('input');
//this inputs array is of course empty so far. Here the tested part ends...

//note that these vars will hold the radios of shipping options, "pickup" ("flatrate_1---0"), "dpd" and "dpd2" are hardcoded shipping method names.
    var pickup, dpd, dpd2;

    for (i = 0; i < inputs.length; i++) {
        if (inputs[i].type == "radio") {
            alert("value = " + inputs[i].value);
            if (inputs[i].value == "flatrate_1---0")
                pickup = inputs[i];
            else if (inputs[i].value == "dpd---0")
                dpd = inputs[i];
            else if (inputs[i].value == "dpd2---0")
                dpd2 = inputs[i];
        }
    }

    //if someone alters the methods so that these can not be retrieved (or for another reason), don't do a thing
    if (cash == null || bank == null || cod == null || pickup == null || dpd == null || dpd2 == null)
        return;

    //don't know if the syntax is right - havent tested this - the idea is clear I think. The function called is below
    addEvent(pickup, 'click', function() {
        cash.disabled = false;
        bank.disabled = false;
        cod.disabled = true;
        cod.checked = false;
    });

    //a similar thing with addEvent(dpd... and addEvent(dpd2...
}