Instead of Superfeet, you could try just putting a few layers of tape (or if you have a lot of space to fill, adhesive foam, like Moleskin) under the insole on the inside side (on top of the inside edges) of your feet. Essentially, what may be happening is that you don't currently support much of your weight on that side, so your feet tend to tilt in that direction. This occurs because the foot bed, with the insole on top, does not match the shape and/or tilt of the bottom of your foot, when you are properly balanced. (Complication: unequal pressure along the sides of your boot, from other foot/boot shape mismatches, can do it too.) On top of that, the relatively low pressure on one side means you don't have as much control as you could over sideways movement of the blade. If you really want to get into it, you can try and figure out whether you have properly balanced pressure when you are balanced over different parts of your blade - like when you are gliding, turning, spinning, twizzling, jumping, or landing, and try to improve all those things by experimenting with careful strategic placement of tape and/or foam.
There is very little difference in theory between using a custom orthotic, a heat-moldable orthotic like Superfeet, and adding a few pennies worth of tape and/or foam. Once you learn to feel what parts of your feet have more pressure on them than others, it only takes a few minutes to modify your insole to do what you want.
That's a bit simplified. A real medical expert, like a sports podiatrist who specializes in skaters, may do a lot more than help you feel more comfortable, and move and balance the way you want. E.g., he/she may be looking for other unhealthy issues associated with movement, like the alignment and motion of your knees, hips, and spine, the way you use various muscle groups, and for a variety of immediate and long-term medical problems. The few hundred dollars he/she may charge for a custom orthotic isn't really just for the orthotic, which may not be in effect any different from a few pennies worth of tape and/or foam - it's for the training and expertise to look for those things. But if all you want is to change the way you move and balance in ways that you clearly understand, and to feel more comfortable doing so, you can probably do it yourself on the cheap - provided you don't have a medical issue that makes your feet too numb to feel where the pressure is.