I have the BassIQ in HighQ setting, even, to help it be more noticeable. I figure if I'm trying to sound effected, might as well go all the way. The attack is set fairly fast, although not all the way. Threshold is the whole key. I fiddle with the setting everytime I plug in. And sometimes even then, I have to readjust in the middle of a set. There's a pretty narrow band where it will do the expected thing, and outside of that, will just go whoop or zhoof, or just do not much at all.
You have to have your input volumes set where they're really going to be, and be playing as hard as you're really going to be playing, to set the threshold right. I have it in my effects loop after the preamp and synthwah, but before the EQ. The synthwah does a good job of maintaining the signal strength, so that they can be used in combination or apart. (I didn't happen to use them together that night we recorded, but sometimes I do) So I can find the threshold with the actual output set low. Amps without seperate gain/level controls, you'd have to pretty much do this at full volume.
If it's not working in the middle of a song, try playing harder or softer until you get it, and hope you can get away with that volume. Moving the plucking spot up and down the string can help find the trigger as well, without changing volume so much.
