You could all try this new method claimed to be working but as I have not lost my IMEI I can't say, please report back if it works for you?
In the meantime, i found "/proc/config/imei/", a folder in wich my imei is actually stored correctly. I also found reports of a file "/data/property/persist.radio.imei". I tried to set it by "cat [imei] > ..." but it didn't work.
Does this help any of you?