Unless you've purchased 99% ipa please realize most IPA is only 70% alky and 30% water and I don't think you want to be adding this into your tank and running it through your fuel system. Have you considered running a 20-30% misture of xylene or toluene instead? Octane for these 2 is in the 114 to 117 range.
You don't want to add alky to your gas. You want to add xylene. As BKS stated put 5 gallons of xylene with 10 gallons of 93 octane and you'll end up with around 99 octane, with about 2 ounces of MM oil
30% xylene is the max percentage I've heard you would want to run so yes, something along the lines of 2 or 3 gal gas mixed with 1 gal xylene would give 33% or 25% xylene and a very nice boost in octane.
I personally like to mix some rubbing alcohol in with a full tank of gas just for the fact it gets rid of the water in your gas.Seems to make my car run so much smoother.Feels like a octane booster when you get rid of the water in your gas. Don't knock it till you try it.Just my opinion.