How to do Redundancy Analysis (RDA) in SPSS?

I am using stats to assess data collected for my dissertation - looking at invertebrate families and how their community composition is affected by habitat.

I've been advised to carry out a constrained ordination or RDA, with the taxa as response variables and habitats as explanatory variables. Please can anyone advise if this is possible to do using SPSS? I have already transformed my taxa data using the Hellinger transformation.

I know PCA can be done using SPSS and RDA is a similar analysis to this - can anyone please help and let me know if and how this can be done? Any advice at all would be much appreciated as very stressed with my dissertation deadline coming up..:(
I see you posted this query some time ago, hopefully you managed to get an answer. I too am wondering if you can carry out an RDA on SPSS, if you managed to find out an answer could you post it? :) Any help would be great! Josh