Need help doing complex transformations on variables to do a regression

I need help doing some transformations on variables--I am kind of real rusty in logarithms and that may be the way to set up this complicated regression. Let me tell you what I do all the time--I can do multiple linear regression all day long and I know how to set up in Excel multiple power functions that are like this Y=aX1^b X2^c all you do is take the logs of your variable and stick them in new columns and then you do the regression of those and I know how to use the coefficients I get from the regression. But here is the deal I don't remember logs too well and I can't find any books or papers online but I just want to do a regression that is like this and I have no idea how to set it up. Here is the type of regression I want to set up and do Y=aX1^b - cX1^d * X2^e. So there is a minus sign in that equation and also a times (multiply symbol). I hope that someone might be able to help me set this up--I know for a fact that this model is the correct model to use.