Jut an update for anyone using eSignal with a similar problem. Use a 390 min chart (the number of mins in NYSE trading session) and set you time to the correct session and you get a pretty decent representation of the real highs and lows of daily spread bars. One problem I ran into is that eSignal only has 120 days of intraday data in the standard data subscription, so I've added extended data which gives you more than enough intraday. Once you construct these bars you can export the data into a spreadsheet as well for analysis. I usually only use this when I absolutely have to, otherwise eSignal gets really bogged down. I hope this helps.
You can have a look at Neoticker. It can draw all the charts you want and can also use bid or ask prices to construct charts. For spreads its not point&click though, you have to tell it exactly what to do using its formula language and it sucks for order-entry. But for charting, its really a very flexible tool.
CQG has two methods of charting the spreads - one (Spread bars) allow you to chart the spread between bars of underlying instruments. For example you can select to build 30 minute bar chart displaying the difference between 1 minute bars of underlying instruments. The second option is to use the SPREAD function that will allow you to chart the spread between instruments with millisecond precision. You also can specify whether you want to use Trades or Bid/Asks when deciding how to calculate the spread. This method allows you to combine the spread with up to 40 legs. And you can build not only timed bars but all other chart types CQG supports (Constant Volume, Market Profile, Point&Figure, TradeFlow, etc.). And, because you can trade the Spreads from CQG directly one can have the complete package for analysis and trading in a single product.
CQG is still the undisputed champion of spreads. Leading the league in at LEAST six statistical categories.