Take a look at Sierrachart. You can add a spreadsheet as a study and get it to draw things on the chart based on info. on the spreadsheet. When you add the spreadsheet, it automatically puts the price data into the first few columns as well as the values of any other indicators you have on the charts. So you can put in your own formulae to manipulate the price data.
You CAN use Excel but they have developed their own version based on the Excel engine. In most ways it is identical to Excel, but it does not have the VBA underbelly. If you want to use VBA you would have to specify that you want to use Excel (this is a parameter setting when you add the spreadsheet study.
Incidentally, you can actually trade from Excel via Sierrachart. It's all there.