Ok- this is kinda tricky and kinda arty.
Find the exact place in your replacement paper as the spot(s) you are patching,.
Cut the replacement paper about 1/2 + inch larger in all dimensions. if there is something in the pattern ( a line, a leaf , a something) that you can follow a cut along, it helps ALOT for hiding the cut. if you are near a regular seam, go to that.
take some vynal to vynal ( or border adheasive) and put on back of replacement peice.
VERY carefully put this peice in the exact position on wall.
Using a new sharp single edge razor ( they are sharper than the break offs), following the pattern as above or otherwise just straight and clean, perhaps using a 4-6" knife for guide, cut the shape through both new and old.
Remove new peice, and carfully remove old underneath on your cuts. might require also removing backing paper using water. Carefully.
Re apply glue and put new peice in place, which should be an exact match, use a seam roller lightly to blend in edges. sponge clean.
And may the force be with you!! And you have just put in what us 'ol boys call a dutchman.