Temporary WorkPermit France for group company mobility

[roystand]

hi all
i would like some help about this topic.
My company group has subsidiaries around the world, in many projects we need to have colleagues from other European (Romania) and non European to come over delivering consulting services, for 2 to 3 months in France.
In this context, the business visa does not fit, and we would like to process work permits for the same. My non French colleagues remain employed with their home country company, and return to their home country after the 2 to 3 months period.
I have searched for processing these work permits but it seems in France they mixed it with same conditions as if the non French are taking permanent employment in France, which is not the case at all...

Can somebody give me some hint about this ? especially hot to establish professional workpermit for 2 to 3 months in France, related to consutling services (whose profiles are not available in France)
thank much
Roy