Possible? Yes. Good idea? Probably not. Lets explore.
It would not just be as easy as a transmission swap. Your talking replacing computers as well. I'm not sure which ones, but for all we know they could all be propriotary to the CVT. You'd also have to replace the linkages for the shifter and get the manual fork and such. Then if you wanted to do it correctly you'd have to change out the instrument panel display as there are different ones used for the manual and CVT. Don't forget the clutch master cylinder, pedal and all related accessories. Also, I could be wrong on this, but it looks like you'd also need to remove the engine in order to get to the transmission.
Now lets examine cost. From what I've been told the cost to get a transmission replaced is about $2,000. Majestic Honda has it listed for $1568. So obviously there is a lot of labor in there (there's a reason I'm buying the extended warranty). The whole shifter fork assembly with all the nuts and bolts needed runs about another $275 when everything is all added up. The LED assembly runs about $675, this is assuming you could get away with just replace that and not have to replace the whole unit, which runs more like a grand (again extended warranty). Now add in about another $300 for the clutch pedal assembly and clutch master cylinder and all related hoses etc. Also, you'd have to replace the brake pedal with the smaller manual transmission one. Now as far as which computers you'd need to change out I'm not sure. I guess you'd have to pull up the nanual and cvt cars and compare part numbers of all the various components. I know the CVT cars are set up to not lean burn so probably at the least the ecu would need replaced. Probably several other computers play a role in cvt stuff, this would require some deep investigation though. You probably dont even want to know what all those computes might end up costing.
Now, if you could find an Insight in a junk yard you might have something there. It would deffinitely be cheaper than getting parts form Honda. Still to get everything right it would be quite an ordeal. If you did do it you'd deffinitely be the first to undertake such a project. I recall this was discussed on Honda-hybrids yahoo group not too long ago and it ended in a quick way too complicated. Thoughts anyone? I could be wrong on some of that, but to the best of my knowledge thats what'd have to be done. If you waited for an 04 you could be the first to get that new blue color they are apparently bringing to the US.