Aliasing can also mean that samples taken on a slowly changing slope can be rounded up/down to the nearest ADC resolution bit, if that is what the OP is asking about then I'd leave some HF noise in place (don;t use too much low pass filtering) and sample at a higher freq than the desired samplerate, then average samples in software to give you higher resolution ADC data.
For instance if you need 1000 samples a second then sample at 8000 samples per second, and add each set of 8 samples together. It will do a similar job to hardware filtering but will remove the aliasing caused by the ADC rounding.