I think you could do it with the following construct:
Hyperreal numbers are parts of polynomials with real coefficients over the variable w , where w denotes the "least" infinity (that is, not the product of the smaller infinite numbers).
Polynomials are ordered lexicographically, i.e. the highest degree to which polynomials differ determines order. This can be extended in a standard way to numerical polynomials (for example, order on rational numbers that are parts of integers).
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