Extra trick: the AHD envelope can also have its times controlled via CV. The standard for this is 1V/10x, meaning that for every additional volt, the envelope gets ten times longer. For example, if you set the decay time to 100 and then send in a value in the range +/- 1 (e.g. from cycle~ 0.1) to the decay CV input the decay times will be scaled from 10 to 1000 ms.
This also allows you to make really long envelopes simply by adding more volts to the input. Need a ten minute decay? (600 sec = 600,000 ms) Set the decay to 600 ms, then connect a sig~ 3 into the decay input. (10^3 = 1000)