How to hash an integer value and later compare it with another value in the circuit?

[aayux]

I couldn't find a way to use MiMC directly on unint64 types. At the moment, I am doing the following:

num := 1248731432
numBytes := make([]byte, 8)
binary.LittleEndian.PutUint64(numBytes, uint64(num)) // convert to byte string

H := hash.MIMC_BW6_761.New()
H.Write(numBytes)
dig := H.Sum(nil)

The problem is that I would later like to be able to compare the integer pre-image of this hash with a frontend.Variable (IsLessOrEqual) whose value is another uint64 type. Is there a straightforward way to do this? It is unclear to me how numerical values can be hashed in both the frontend (the circuit) and the backend (the prover).

Secondly, I am unsure if using uint64 values will work correctly with the curve arithmetic. Should I be computing everything modulo something?

If it makes a difference, the integer values are actually the int64 outputs of time.Now().Unix(), the current time in Unix format.