You can't train your chin not to chew on things, it's up to you to make sure things that would be dangerous to chew or eat are not accessible. You can use fencing to block off areas or even use a playpen instead so the chin is contained and can't access the cords. In extremely rare cases people have claimed to convince their chins not to chew on certain things, but in almost every case those same people come back later sad that their chin chewed on a cord and got electrocuted. Or they claim their chin knows not the chew on things, and in reality they have trained their chin to just not chew on anything, or have a lazy chewer. Their teeth grow all the time, so they need to chew on things to survive, chins are not like something like a dog that you can teach to only chew on their toys.
Some people use the bathroom for playtime, that room tends to not have lots of cords and is easy to clean up. I know that doesn't work for everyone though, not all bathrooms are well designed and some have holes in the walls that chins can go into making them unsuitable.
Keep in mind though, any time the chin is outside the cage you should be watching it 100%, as in not leaving the room even for a minute and not doing other things while the chin is out. If you can't have eyes on the chin it needs to go back in the cage, so you should also be able to stop the chin from chewing on things if they get around or jump over the fencing for example, since you will be right there. I'm not sure what you consider "a lot of time" but for most chins half an hour to an hour is enough out of cage time, and it's not required everyday if you can't watch the chin that day or don't have time for some reason. The cage should be plenty big enough (I would say a minimum of 3 feet long, by 2 feet deep, by 2 feet tall, but bigger is almost always better) and you can also get a wheel (15-16" diameter (or 14" if a saucer style) solid metal not mesh or plastic) so the chin can still get exercise if you feel it needs it. Not all chins are like mine but my current two have a double Ferret Nation cage, lots of ledges, perches and a wheel, so it's not uncommon for them to not even spend much time out of the cage. I can put the fencing around the cage with the cage door open and sometimes they only spend about 5-10 minutes out before going back in no matter how long I leave the cage open.
More important then out of cage time is interaction with you. That should be a minimum of an hour a day every day and can include out of cage time but also while they are in the cage, just talking to the chin, petting them (if they like it), talking to them, handing them treats and chews, stuff like that.
