Tileable textures work for some jobs, but sometimes you need your surface to appear seamless, especially when you have expansive scenes of natural elements like grass, stone and sand. That's when texture replicators come in handy.  

Instead of tiling an image across a plane, the texture replicators new to modo 601 allows you to place a small copy of the image at each vertex. From there you can randomly scale, rotate and blend them to make the surface appear seamless.

Here is a simple example that will hopefully get you on the right path, however if it doesn't address all of your questions, maybe the video links below will.

It's assumed that you already have your terrain or whatever mesh item you wish to apply your texture to.

James has recorded two videos on Texture Replicators. The first shows how to make a seamless grass plane, and the second explains texture bombing where you use multiple texture images under a single material.

MutantPixel (James Darknell)