I'll do my best....basically, if you have a valvebody that locks at the bottom of 2nd, you can do that, but the slip rate on the converter might be 50% or more, so it's the same on the converter clutch as trying to slip a regular clutch, so it's easy to fry the converter clutches. Plus, the 1-2 shift is usually less than 100 feet out, where most diesel trucks on diesel tracks have a hard time hooking anyhow, so no need for more HP.
Anyhow, a timer can be used to trigger lockup on the 1-2 shift, but delay it up to a second after the shift in order to get the slip rate on the converter down to 20-30%, thus vastly increasing the life of the converter clutches. Something like this cheapy $40 deal from Summit can be wired in.
ARC-Auto Rod Controls 1402 - ARC Time Delay Relays - Overview - SummitRacing.com
These ARC time delay relays feature a plug-in fuse and 40 amp relay along with an adjustable 0.1 second to 1.0 second time delay, in 0.1 second increments. They enable you to minimize engine and driveline damage, while improving drivability. You can time-delay a stage activated by a shifter switch until after driveline loading peaks, the clutch locks up, and or the tires hook up. You can also activate two stages by the same switch, delaying the second stage to lessen the motor and driveline stresses.
They mention lessening driveline stress in respect to nitrous, but lockup on our trucks is kind of like the same thing....another 200hp or so at the press of a button.