Aarons Bicycles may be able to help you with the needed parts.
http://www.rideyourbike.com/internalgears.html
Per my understanding they import Sachs/SRAM parts from Europe that are not available here through normal distribution. Per the SRAM parts manual the 3 speed trigger shifter is still made. The current SRAM T3 is basically the same as the old Sachs dreigang so the SRAM T3 twist shifter should work too.
Another possible american source is Yellow Jersey.
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Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
Visit and join the Yahoo Geared Hub Bikes group for support and links.
http://groups.yahoo.com/group/Geared_hub_bikes/