creating tempo grid to freetime piano performance?

Does anyone know how to generate a tempo map for a free time piano piece, recorded in midi without a click? The idea is that I'd like to create an orchestral score around the piano piece, which fluctuates beautifully in tempo. Having a grid to score onto would make life a whole lot easier, as i'll be scoring the whole thing in midi. Can i somehow tap along, with all the ralls & accelerandos, & have protools track that accurately & create a complex tempo map? Any ideas on how to do this would be a revelation !! Thanks Gio

Try using midi beat detective to grab all the midi notes and spit out a complete tempo map. Should be quite easy.

Or you could go through and manually identify the beat on a per note or per measure basis as needed using Command+I. It might take a while but would definitely be accurate.