In general? Not worth it. "In the wild" (harr harr) the ancestors of guinea pigs are roaming herd animals. They don't generally nest (their young are born walking and eating, like our pigs) so they have no need to have much of a litter instinct.
Overall, they're not really trainable. I have known one or two that were, but they were unusual pigs and weren't ever trained, they just picked a corner and stuck to it.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry