The technique I use requires a couple of spring clamps (available at "home depot" type stores) and a brayer (roller). Unlike most tutorials, I don't expose the adhesive prior to aligning the print to the lens as I prefer to align the print to lens, clamp the two together and then start the laminating process.
The first task is to align the lens to the print. Assuming the lenticular lines run vertically, you want to make sure the print and lens are aligned horizontally so that you properly see the scene in the interlaced print in 3D. The left and right alignment marks are there to help you align the print and lens rotationally: the left and right alignment marks should be solid, in other words, you shouldn't see bands. Don't worry about the top and bottom horizontal alignment marks as their usefulness is quite limited. Once you have the perfect alignment, put a clamp on the upper left and recheck the alignment. If all is well, clamp the lower left.
We are now ready to laminate the print to the lens:
Put a piece of tape on the lens release film at one of the two right corners and pull it back until about one inch of adhesive is uniformly exposed over the width of the lens.
Tape the rolled back release film to the lens.
Now, most tutorials would tell you then to lower the print to the adhesive over the rolled back release film. Well, I don't do it that way because I just don't like the idea of going over the rolled back release film as it could introduce a shift width wise, which is really not good since it's the 3D direction (if it were in the other direction, it wouldn't be a problem).
Cut (with a pair of scissors) the rolled back release film making sure you hold the print away from the lens.
With a brayer (roller) and with the print back facing up (you still have the clamps so you may want to do this at the edge of a table), press the print onto the lens starting from where you cut the release film. You have to be careful not to create bubbles so press hard on the brayer and never let go of the print until you are at the end. If you don't have a brayer, you can certainly use a squeegee type of thing.
Remove the two clamps.
Remove the rest of the release film again taping a piece of tape to a corner and pulling the release film back while keeping the print away from the now exposed lens adhesive.
Press the print onto the lens starting from where you had cut the release film (going the other way this time). Again, be careful not to create bubbles.
At this point, you may want to use a squeegee type of thing to get rid of the silvering effect, or at least, reduce it.
That's pretty much all there is to it. If you have a cold laminator, then you can't cut the release film like described here, you have to press the print over the rolled back release film.
After the lens is aligned to the print, the two are held together with two clamps.
This is what it looks like after the release film has been peeled off and taped to itself. Use a piece of tape at a corner to lift the release film. Next step is to cut the release film right at the crease.
Here, I am bout to peel the rest of the release film. The piece of tape in the middle of the film is the one that was used to hold it when it was peeled back (it may have been removed when you got rid of the smaller piece of release film).
Video showing the resulting 3D lenticular lens.
You have to be aware that doing 3D lenticulars with just a left and right image is not ideal. It would be better to have intermediate images that morph from left to right and interlace all those (intermediate images are not easy to get but there is software that claims they can get them). With just the left and right images coming from the mpo file, you're gonna need to look at the lenticular print straight on, in other words, you can't just look from the side and expect to see anything 3D (multiple frames would allow you to do that).