Emblems are created by effects, usually through a planeswalker's loyalty ability. If you can find a way to create IN GAME an effect that creates an emblem, sure. But planeswalkers are the only way to my knowledge. You cannot bring emblems into the game just because you feel like it.
Like the token cards, the emblem cards you find in booster packs are not actual Magic cards, you can't put them in your deck. They are just game accessories: you may have them on the side, they're practical and nice to have, but they are optional, just like, say, a playmat. Like a token, an emblem will always be created by the effect of a card, you can't just "play" the emblem card. Conversely, if you don't have the official emblem or token accessory card with you, you can use any reasonably fitting object, like a random piece of paper on which you write what it is, to represent an emblem or a token.
I'm a former judge (lapsed), who keeps up to date on rules and policy. Keep in mind that judges' answers aren't necessarily more valid than those of people who aren't judges; what matters is we can quote the rules to back up our answers. When in doubt, ask for such quotes.
Former Rules Advisor
"Everything's better with pirates." - Lodge
(The Gamers: Dorkness Rising)
"Any sufficiently analyzed magic is indistinguishable from science."
(Girl Genius - Fairy Tale Theater Break - Cinderella, end of volume 8)