Why can we use にせよ in this situation?


If I'm not mistaken, にせよ is more or less にしろ and they can be used like にしても.

The thing I don't understand is that normally in Xにする, X is a noun but in this
sentence にせよ is used right after a verb in dictionary form(without よう or
anything like that) :

> 何をやるにせよ、ベストを尽くしなさい。 No matter what you do, do your best.

