MaxiFi does not have an option for after-tax IRA contributions.
close to a Roth for the contributions and for some of the money at withdrawal time, but the earnings part of the withdrawal is taxable (unlike a Roth). You could set it up as a Roth (MaxiFi does not prevent you from contributing to a Roth based on any income rules), but then you'd need to create a special expense to represent the under payment of tax for each year you withdraw, which you'd have to calculate on the side and set up as a series of annual special expenses.
You can leave all the money in a traditional IRA and then use a special receipt for the tax credit or you can split the money between a traditional IRA and a Roth IRA and then use a special expense for the additional tax.
Either way you have to calculate a tax adjustment.