If I understand you in the right way, the key is to create a piece of artwork,
1) With the desired dimensions, one being the width and one being the circumference of the roll;
2) Starting and ending with the same part of the repeated artwork, preferably with an empty strip or a simple part such as lines in the lengthways direction so that an inaccuracy (especially lengthways) can be hidden.
Hmmm... kinda. It's not really to 'hide' any 'inaccuracy,' but in effect that is indeed what it would do. It would essentially be 'borderless.' Also, I don't want to be limited into making a "roll" as that implies that it would only be borderless on the left and right edges. I would want the wraparound to work for the top and bottom borders as well.
Looking around the web since I posted, I believe what I am looking for is to make a "repeating" pattern with a "seamless" edge.
Another example for which I thought this might apply: a pattern for a webpage's wallpaper-background. It is often a small tile, that is repeated many times over, both left-to-right and top-to-bottom. The edges are seamless.
Rather than confusing the dialog any more than I already have... I created two illustrations that will hopefully make it more clear.
If I get it right this time, it sounds as though you can find the answers in the Helpfile itself, if you look for Patterns, more precisely Brush (and Fill) Patterns and Pattern Tile.