So below are the steps that I made, which all seems to work well but this is with over writing COD. If you need to have this one too, then copy these files and rename them. There will also be additional tables to add. Can't help you there, maybe someone would like to send me how and I will add it within the sequence.
The files to change are as follows:
Warning! Do a back up first!
.../catalog/extension/payment/cod.php
.../catalog/language/english/extension/payment/cod.php
.../admin/controller/payment/payment_cod.php
.../admin/template/default/content/payment_cod.php
.../admin/language/english/controller/payment_cod.php
1) either make copies of these files, or rename them directly if not going to be using the COD mod.
i.e.
.../catalog/extension/payment/cod.php
to
.../catalog/extension/payment/cheque.php
so on and so forth for all of them above.
2) inside these files change all coding from cod to cheque (or check if you are from US etc).
3) when dealing with the language files make them refer to cheque rather than COD.
4) go to admin panel> extensions> payment> either change the cod or add a new payment extension.
>General tab
Extension Name: cheque
Description:cheque
>Data tab
Code: cheque
Directory: payment
Filename: cheque.php
Controller: payment_cheque
>SAVE
5) go to the little wrench far side, and make sure enabled.
6) to stop getting an error of no permission>
>Admin Panel >go to admin > configuration> users> user group> top administrator> little notebook> click >
You will see already highlighted permissions, scroll down on *access and then
> holding ctrl button on keyboard, and then clicking on payment_cheque (otherwise you mayl de highlight all of them) it will now highlight too
>do the same to the one underneath *modify
>SAVE
7)go to your database via phpmyadmin > settings (table)> browse>find the following
cod_sort_order to cheque_sort_order (and elements inside referring to cod table) >SAVE
cod_status to cheque_status (and elements inside referring to cod table) >SAVE
cod_geo_zone_id to cheque_geo_zone_id (and elements inside referring to cod table) >SAVE
That's it really.
If you find that you get an error, do check your permissions, and all your files that all the cod(s) have been changed. When I first checked i got a blank screen and I had missed a few in a file.
Anyway hope this helps, it will of course is just the basic instructions for any of the payment plan, but the obvious coding modifications necessary within files for it to work for what you are trying to achieve..and I can't help there.
