Personally, I would pot them up in well draining pots and allow them to sit outside and let the seasons work on these slow germinating seeds.
Soak them for a couple days after you clean the red seed covering off the tan colored seeds.
How old are these seeds?
They germinate when the adults come up, usually in Autumn. I have to bring the pots with the young plants in and grow them indoors as January and February are very harsh here in Buffalo, NY. I leave the pots out all fall, until I hear of harsh weather approaching, bring them in until March, but pay close attention to the weather forcast...
Check out the International Aroid Society' s website, as they have information in their archives. Do a search as I got information from there.
That is all I know and hope this helps...

Thank you so much. When I got the berries, they were bright red and all the plants on the grounds where in the same state. I would assume that the berries were almost ready to be picked off.
I would have a hard time growing these outside as I don't have a place outside to put them.