I had created a custom visualforce button as shown below. That would pre populate the look up field.
<apex:commandLink value="Create New Order" onclick="/a15/e?CF00N50000003qoqXEAU_lkid='{!Account.Id}'&CF00N50000003qoqXEAU='{!Account.Name}'"/> -->
<form action="{!URLFOR('/a15/e?' + 'retURL=%2Fa15%2Fo&CF00N50000003qoqX={!Account.Name}&CF00N50000003qoqX_lkid={!Account.Id}')}" target="_blank" >
<input type="submit" value="Create New Order"/>
</form>
</div>
<br/>
After clicking the button the output displays as follows
I want the URL to display as
a15/e?retURL=%2Fa15%2Fo&CF00N50000003qoqX={!Account.Name}&CF00N50000003qoqX_lkid={!Account.Id}