On Tue, 15 Jan 2013, Procházka Lukáš Ing. - Pontex s. r. o. wrote:

> (Finally: I'd like to achieve a Lua function which will copy all pages of a 
> .pdf file, keeping size of each page, and adding a customizable string with 
> page-in-the-pdf number (with default value "<page-i>/<n-pages>"), being 
> placed to the right top corner of the i-th page. All to be provided by Lua.)

A few years ago I wrote a module that, amongst other things, did this. 
(The mail purpose of the module was to cut 2 column journal papers to one 
column PDF so that they are easy to read on an eink reader. I haven't used 
this in a while, so it may not work out of the box).

https://github.com/adityam/cut-n-paste/blob/master/tex/context/third/cut-n-paste/t-cut-n-paste.tex

In this case, I used a MetaPost overylay to draw the page number (search 
for cnp:text). The user could manipulate the location of the page number 
by using the location key (which had to be a valid Metapost pair).

Aditya