Probably not, no, considering that's ROM and you can't write to it
Edit: So I'm working on the first-ever DSi-specific game level viewer, which I call Trajectory. It's a level viewer (NOTE: Not an editor) for Trajectile/Reflect Missile. It's not quite finished yet, as I still have some graphics to rip and edit, but once I finish it to the point in which I'm satisfied, I'll probably be releasing my level documentation and the source code, as well as a binary, of Trajectory for people to look at and play around with. Once I get close to its completion though, I'll be opening a separate topic, however, if enough people want me to, I'll open a thread early with a checklist of things that I still need to finish and allow people to discuss it, as well as look at the current (messy) source code.
Edit: Take a look at the most current version: