I have a Sturmey-Archer 3 speed hub I'm going to use on my next build.
has anyone used a SRAM type shifter on a 3 speed hub? (the one that's at the front derailleur)
You may be able to kludge something up where the steps on that SRAM front shifter matched the needs of the Sturmey-Archer, but it's more likely that you'll end up with headaches. Sturmey-Archer 3 speeds come in a variety of options (grip, quadrant, classic trigger, thumbies, bar-con, new-school over/under trigger {pretty similar to the SRAM you linked}, sticks, etc...)
These would all be plug-n-play, assuming you select one that's for 3-speed but NOT the fixed S3X.... no need to fuss with cable pull and shift stops...