Is there any way to override the comparison function in a F# set?

I don't see any set construction functions that take a IComparer<T> or comparison function:

• Set.ofSeq et al don't take a comparison function
• FSharpSet(IComparer<T> comparer, SetTree<T> tree) constructor is internal, because
• SetTree is internal and
• SetTreeModule.ofSeq<a>(IComparer<a> comparer, IEnumerable<a> c) is obviously internal too.

My actual problem is that I have a set of ('a * 'a) and I want a comparison such that for example (1,3) = (3,1).

I know I could wrap this in a type implementing IComparable<T>, but is there any way to avoid this?