AliasSeq of AliasSeq, or meta-functions that take multiple lists

[Jean-Louis Leroy via Digitalmars-d-learn]

I need to process two sequences in parallel (select some elements 
of sequence A depending of the corresponding element of sequence 
B). How can I pass two sequences to a meta-function? I tried 
nesting AliasSeqs but I get Perl4 style flattening:

   AliasSeq!(AliasSeq!(int, float),
             AliasSeq!(char, double))
   -> (int,float,char,double)

I worked around the problem by passing a single AliasSeq to my 
meta-function and using indexation to access the two sub-lists 
but now I need to process three sequences in parallel and I am 
looking for a cleaner solution.