Why not just mentally multiplying the percentages by 2.5 in your head until you're used to them?
For all the reasons earlier in the thread, that approach won't help much.
To show it graphically, the following image shows the percent values in Lightroom 3 Beta 2, followed by the same image converted to ProphotoRGB, AdobeRGB and sRGB in Photoshop.
Multiplying the percent values by 2.5 doesn't give the same values in the different output profiles:
For the specific values, the following table might show it more clearly than the image, including the 2.5 multiplier of the percent values:
The target image can be downloaded here:target.psd