The textbox itself would most likely be found within the code of a file located in the nb store dll file, so to edit that, u would have to open the dll file, locate the vb file (prolly named something with 'product'), find the input tag for the qty textbox and within that tag add "READONLY".
Then u save the file, recompile the dll and upload it to ur working installation.
Another way which can be done in the template, would be to outcomment the models dropdown selector like I did it in the below example, it works, BUT take note that when only one model is left, the page reacts as if the item is out of stock.
So either u have to always have on in stock that u can never sell or u can create a dummy model for the purpose.
Then u save the file, recompile the dll and upload it to ur working installation.
Another way which can be done in the template, would be to outcomment the models dropdown selector like I did it in the below example, it works, BUT take note that when only one model is left, the page reacts as if the item is out of stock.
So either u have to always have on in stock that u can never sell or u can create a dummy model for the purpose.
<!-- Models Dropdown Selector -->
[TAG:TEST:<prop TestType="setting" TestName="modelselector.flag" TestValue="0" Action="Hide" />]
<!--<div class="Models Row">
<div class="Label">Models</div>
<div class="Value">[TAG:MODELS:<prop CssClass="Model NormalTextBox" />]</div>
</div>-->
[TAG:END]
[TAG:END]
<!-- End Model Selector -->