I'll weigh in. Take what I say with a grain of salt and draw your own conclusions.
Talad's post revealed a few answers if you read between the lines.
Is it possible? In theory.
Is it as effective as using glyphs (In Yliakum)? He didn't say.
Are there consequences? He didn't say, but I would assume there very well could be.
Is it as easy to learn as standard magic? No, it would be harder.
If your roleplay includes some form of magic that greatly differs from the game's reality, then you risk turning away players who will want to play within a more conservative view of the settings. I would say that adding your own artistic deviations to existing spells is being conservative, discovering spells that fit into your way is more liberal, while making it rain purple frogs and psychedelic drops of awesome is going to get you laughed at if not ignored.
With that said, your peers who you play with will to some extent, be your judge and jury. They will accept or reject your artistic freedom - keeping you in line with what they feel is plausible. I don't think any GM or settings people will hunt you down with torches and pitchforks if you break settings, but do keep in mind that doing so may break immersion for other players. We want to keep the fantasy world believable and consistent through our character's actions and words.
If you want ideas for how to roleplay the use of known magic, look at the race history, look at the spell descriptions for learned spells. Do the magic way quests. Think about what effects a spell might have - it's look, smell, taste, sound, and feeling. When casting Flame Burst, does the room glow with a warm orange hue as the fireball crackles and grows between your hands? Is it so bright that it's painful to look at? Can you feel its heat as it approaches? Does it smell like putrid sulphur or like fried Klyros fingers ? This sounds a lot better than "/me just stands there and a pixelated 2d image of fire hits the target for 81 points. I leap with tearful joy, for I hath grow-ith in red way."
Back to the original question, ( I do realize this is an old, old thread ) If it's in released settings material - like quests or IC books, and its something than an ordinary ( non-god ) person has done, then I think its plausible that your character could accomplish the same under similar circumstances. I would just be prepared to provide curious partners with the premises that you base this on in the event that they ask.
Whisper Bless!
