IT CAN BE DONEhttp://dffd.wimbli.com/file.php?id=1246This was made in 40d with some mods. I put in orcs, changed all large clusters to veins... and made dwarves with super-speed who don't eat, drink, or sleep, for experimental purposes. The necessary raws are included with the world file.
I successfully passed magma between sites. Walls can't be built near map edges, but drawbridges can! I extended an above-ground magmaduct to the edge of a site by building some drawbridges and raising them.
To visit in adventure mode, start as a dwarf of Ninurzuglar, which is right next to my prototype. You need to be in adventure mode, obviously, to move magma from one site to another, but reclaiming will let you get a better look at how things work.
Udilsakrith is the magma pumping station. My apologies to all adventurers for leaving most of the bridges up, but you can still get in. The control room is one level underground and is a smoothed 3x3 room with levers in the NW and SW corners. The NW corner lever controls the gear, already engaged, which passes power from the wind farm to the main pump tower.
The SW lever needs to be pulled to activate the system and will engage the gear connecting the pump tower to the main intake pumps that pull magma from the bottom of the vent. It will take a little while for the magma to reach the surface, so be patient... and don't go breaking down any locked doors
unless until you want to flood the fort with magma.
Itebsanreb is the middle section of the magmaduct. There is a floodgate in the middle of the pipe which must be opened with a lever. There is not much else interesting there.
Ugoshlolor is the end of current construction. There is a pump which will move magma from the (blocked) pipe into the pit I dug when I was mining the stone to build everything.
Unfortunately, when you move from the second to the third site, the first one is unloaded from memory and magma stops moving. To make a serious "collect all the world's magma" project, you would probably need to put a relay station on every (or at least every other) site with a magma-vent-sized holding tank, and move the entire contents of each vent one site at a time.
Alignment is difficult. To align the pipes in the first two sites, after abandoning the second site I visited the first site with an adventurer, then moved a few tiles straight north and succumbed to starvation. When I reclaimed the second site, the dead adventurer indicated the exact location for the center of the pipe. For the second pair of sites, I simply counted tiles from the edge, but I was wrong by one tile and had to realign things later.
And the magma stays in the new site when you reclaim it in fortress mode. The only trouble is that magma buildings are not enabled. I was hoping to set up smelters and melt down all the steel armor brought by reclaim parties.