"equalizing" 2 different camera files in DPP

OK what happened is this:

I originally had just a Rebel XT, but now I bought an XTi to have 2 bodies. Now I notice that the XT and the XTi render skin colors very differently. I like the colors the XT renders so what I've done is a recipe that plays with each of the channels in curves (among other stuff like desaturating -3 on the raw panel) but its not perfect I still can notice the difference.

I would like to know if there is an easier way (done in DPP, no "use ACR or lightroom" answers please). Also Does the xrite color checker passport work in DPP or just in lightroom/ACR?

The XT is from before Picture Styles were introduced to Canon cameras. The Neutral P.S. is supposed to produce color, saturation, contrast and sharpness similar to pre-P.S. rendering, so if you shoot jpgs you can set the XTi to Neutral to obtain near uniformity. Alternatively, if you shoot RAW, you can convert in DPP and as long as the shots from the two cameras are rendered with the same P.S. they should be very similar. You can take this further by downloading Canon's Picture Style Editor and creating custom P.S. files for each camera that will produce exactly the rendering you like. The thing with the Color Checker Passport is that its accompanying software will save profiles in the format used by LR/ACR. It will not produce Picture Styles. However, it will make an excellent test target with known color values if you seek accuracy from PSE rather than an eye pleasing rendition (the two are not always the same.)

Thank you for the answer. I will try the neutral PS to see if it makes a difference. I will also download the Picture Style Editor and see if I can do something better than the curve adjustments in the RGB tab

EDIT: I tied the neutral PS but it still isn't quite as close as the curves adjustments in the RGB tab, still going to try the PSE to see what can I get.