Generally speaking, we leave the handling of fan art around here to Tabby. But in this case-- a more functional case than the norm-- we figured that something a little more front-and-center would be in order.
So, as it stands, it looks like Capcom has no interest in putting Mega Man Legends 3 on the Nintendo 3DS (or anything else, for that matter). However, that doesn't mean you cannot still show support for the game and series by putting it on your Nintendo 3DS another way.
That brings us to the above Nintendo 3DS skin by ArcAngeRaziel on deviantArt. You can find the above skin in a zip file, as well as instructions on how to create your own (for this, or most any other current-gen console/handheld, and for a price) here. Of course, if you opt to print it out yourself, you'll undoubtedly need a special type of adhesive sheet to apply the design to... so, good luck with that!
And just think: if you show up to some sort of event where Capcom representatives are in attendance, you can show off your own custom Nintendo 3DS, covered in love for Legends. Subtle? Who wants subtle? We just want Legends 3.