Citroen Hydropneumatic suspension......Other Cars?

There was a Pro Street Corvette in Street Machine donkeys years ago that had it fitted to the front end. I think for the time and money you'd need to spend to adapt it to fit you might as well use bags.

It's possible but difficult. The best way to 'look' at the system (the BX system being the 'easiest') is to pick up the BX Haynes manual for the flow circuit diagram. Be aware that there is a lot of pipe work to and from everything, and a lot of other parts as well as a pump and height correctors, you will have to have the accumulator and depending on how far you went, the safety valve and FDV. Also to bear in mind that the hardlines are a special proprietary flare and seal, so it's hard to make custom pipe work, and finally the BX strut towers are dropped into the bodywork by a fair amount to accommodate the spheres under the bonnet. As matt said, it's possible, but in today's day and age a cheap airride kit would be easier.