Yes you can include the qty on hand field on the product list page. If you open up productlist.ascx and add the following line to your desired location in the datalist it should work for you:
<asp:Label runat="server" ID="lblQtyOnHand" Text='<%# DataBinder.Eval(Container.DataItem, "QuantityOnHand").ToString() %>' CssClass="SmithProdText"/>
If you like us to create a new buynow setting to add it for you please send an email to sales@smith-consulting.com.
-Scott