On cars and trucks these days, you can disable traction control using the skid control button. (On my Toyota trucks, you have to come to a stop, and hold the button down for 3 seconds.) This gives you an open differential, which is useful at times when you just want to spin the wheels and not have traction control fight against you, like in deep sand and snow.
I find that i4WD is almost useless in the sand! Say the left tire is slipping (something is always slipping in sand!). The system brakes that wheel and transfers the power to the right wheel. Then the right wheel slips, and it brakes that wheel and transfers the power back to the left wheel. And so on...back and forth all day long! This causes a kind of back and forth jerking of the front end, and doesn't really do much to help you get up a dune.
So is there a work around this? Is there a way to get the same effect as holding down the skid control button???
No, you cannot disable i4WD. You can pull the fuse but you loose all 4WD totally because the same circuit is used to electrically engage the front diff. Someone was trying to make a manual engagement switch a whole back but didn't get anywhere so they quit trying.
That said, there might be something amiss with your machine. I have over 3000 miles on my machine and about 2500 miles of that at the sand dunes. I have tried stock tires, 30" Tusk Terrabites, some cheap 28" paddles and now on 30" Skat Track Extremes. At the dunes, I use i4WD about 80% of the time and not once has my machine exhibited what you describe.
In the sand with the Skats, my machine goes good in 2WD. In i4WD, she goes fantastic and I have absolutely no back and forth jerking and she drives perfectly straight when pulling a hill of any slope (as long as the sand is somewhat smooth). If not smooth, it has a tenancy to follow other tracks but that is completely normal and any machine does that. There are5 other Talons in our group and about 10 other Talons at the dunes I frequent and in almost 2 years, not one of them has ever mentioned anything like what you describe.
A possible telltale sign that your i4WD is overworking is front brake pad wear. My brakes are still factory (3000+ miles) and are only about 1/4 worn and most of that is likely from other activities such as trail riding and rock crawling and not duneing.
For those reasons, I would suspect something isn't working quite right with your machine.
I was taught one trick by Jeff Proctor to get your i4WD working at its best. Thoroughly bleed your brakes. He said that the race team Talons both worked noticeably better after bleeding the brakes. I tried and noticed a big difference in how the brakes stopped the spinning tire in the slick stuff and rock crawling. Much faster response, less ABS motor chatter and better traction. Seems like there may have been a tiny bit of air in the system. I guess the factory doesn't put a lot of effort into bleeding the brakes. You may want to start with bleeding all the brakes and see if that helps at all.
