seing as tho the 3dr geometry is completley different, and so are the EPER numbers for the seat cusions, i'd think not...but i'd wait for someone who knows to chime in.
You can fit 3 door seats into a 5 door Stilo. I've just done it with a nice set of leather sliding rears with armrest and the two fronts. The fronts went in easily but I had to mess around with the seat belt to seat fixings as they are different, it was pretty straightforward as I just bolted them to an existing bolt fixing and trimmed the plastic to allow for the seat belt now attached to the seats. The rears use nuts and bolts on the front and just bolts at the back whereas the old 5 door rear seats used nuts and bolts on front and rear fixings, also the rear fixing holes are in a different location and were blanked out with plastic so I had to remove those. Another problem was I didn't get the bolts with the seats so I'm 8 bolts short, they are 10mm fine thread so I'll be off to the scrappers to see if I can get some to finish the job.
Final issue is the airbag warning message that is now coming on every time I start the engine, everything connected up fine, like for like but it is something I may need to look at. For now I just hit the 'Mode' button as I well know Fiat electrics have a mind of their own.. Hope this helps and I will try to post some pics when the job is finished.. They do look nice..