Question about pagination on CI3

I am a little lost with CI3 pagination.

Let say I have

Code:

http://example.com/test/page/1/category/item_id

using the 3rd segment as the page number (page 1, page 2, page 3, ...)

$config['uri_segment'] = 3;

I know the documentation says how to reuse the query string like this

Code:

http://example.com/index.php?c=test&m=page&per_page=20

 
But that is not working for me. So my question is how do I pass the /category/item_id segments or additional segments on the pagination numbers?

all I got so far is

Code:

1 = http://example.com/test/page/1
2 = http://example.com/test/page/2
3 = http://example.com/test/page/3

and no /category/item_id segments after the page number

Thank You!