Look them up on realoem or bmwfans and order from the BMW dealer/parts supplier of your choice? I suspect the springs, shocks and perhaps ARBs are different from the "standard" E61s and the M5 E61 but just about everything else is the same?
Looking at your avatar you have a 535xi. I'm guessing that you want to fit some E61 M5 suspension parts to your 535xi? There are numerous differences between the 535i and 535xi which makes me think numerous M5 parts won't be a straightforward install. If you want to improve the handling perhaps look into shocks like the KW V3s.
You are right, I was thinking if you can use M5 suspension parts on e60's why not M5 535 xi touring on 535xi's touring. I have HR sport spring on front and riding on Bilstein sport struts all around. Just thought M5 touring parts might farther improve handling performance. Somewhere I have read that M5 brakes can be adapted to 535xi wagons. What is your take on the M5 handling mods?
I had an early E61 535d sport which I always thought wallowed and swayed too much. I was well aware it was a 4000 lb car but thought it was too soft. When I first drove an E61 M5 I had sort of a Eureka moment in that the car rode and handled like I thought it should - firm and controlled yet still composed and compliant enough for day to day use.
The front suspension on the xi is quite different to the RWD car because of the extra drive shafts. My suggestion is to explore the 5series.net board where people have posted their results of mods like the KW V3 on AWD E60s and E61s. Good luck with your search and mods.