Just enable them on form submit.
Like…
This is the disabled select box:
<html:select name="enrolmentForm" property="pay" styleClass="droplist" disabled="true">
<html:options collection="arrlstPayOptions" property="idpay" labelProperty="valuepay"/>
</html:select>
<a href="javascript:submitForm()">Submit</a>
Now as it's disabled but has a value that needs to be submitted, That disabled value will not be propagated to the java layer.
To make it persist you need to enable it just before the form submits... like this
function submitForm(){
document.frmTab.pay.disabled = false;
document.frmTab.submit();
}