I don't think there's a way to do what you are asking to do... but generally, the resampled version should have the same start point (sometimes a bit quicker on the attack) with a longer time before the end point. The thing is, the added length on the end shouldn't really be a big deal due to the fact that it's just empty space. So triggering the new sample in your seq should still sound more or less the same as far as when the samples are being triggered... unless the effect you add has a lot of additional noise that has added length to the original sample.
side note: truncating marked samples is a helpful feature... not that it's what you're asking about. hit the pad for the sample you have marked... then hit del, mark, del... and it will trim the sample to the marked end points.
Hope something in there is helpful.
