Implementing anti-aliasing in waveshaper patch

Hi,

as quite a newbie to Max I have done a nice wave shaper, however it suffers terribly from aliasing and I would like to address this issue. If I understand the sampling theory right I need to oversample the signal, process it, filter out frequencies above Nyquist frequency and downsample. However I have some questions regarding the implementation:

How to accomplish oversampling and downsampling in Max?
Should I use one of the stock Max filters or try to build a brick wall filter using FFT techniques?
If you would opt for the brick wall filter could you please recommend some related tutorials? My highest achievement yet with FFT was building an amplitude filter and I am not really familiar with Jitter.

Thanks in advance.

Samuel