Here is my final solution for those that might want to know:
In Confirm.ascx
<div id="btnSubmitDisabledContainer" runat="server" style="visibility:hidden; float:right; cursor:wait;" >
<div class="b_left"> </div>
<div class="b_center"> <asp:LinkButton ID="btnSubmitDisabled" runat="server" CausesValidation="false" Text="SUBMIT" CssClass="b_link" UseSubmitBehavior="false" resourcekey="btnSubmit.Text" Font-Size="12px" Enabled="false" style="text-decoration:none; cursor:wait;" /> </div>
<div class="b_right"> </div>
</div>
Seems to work, but I'm not css expert.
Now hopefully customers will just wait for the transaction to complete and not think the button is broken.