Attention to itching makes me unable to focus on anything else

I struggled with eczema and itching for many years. I felt that watching the itch for as long as possible can be some kind of game. Watch what feelings and sensations come up. Sometimes my whole body would be going crazy, tingling, almost shaking that it was almost funny. Then I would calmly walk up to a mirror and investigate that itch very very carefully. My eczema almost disappeared this way. I felt as though this helped train the mind in what was important and what was not. Sometimes there might be a stray hair, sometimes a flake of loose skin or sometimes some inflamation.

This experience is quite normal. In addition to itching, there are many more bodily functions. One of the monks said that it is called Dathu Manasikara. Actually this is a sign of your progress in meditation according to him. Do you see the itch come and go or it moves to some other place sometimes?

In Chapter 10 of Mindfulness in Plain English, Bhante Gunaratana speaks of itches and other troublesome sensations, specifically in the context of meditation, saying “Watch it come up and watch it pass away. Don’t get involved.”

I often get itches during meditation, and I find that if I simply unattach from the sensation, not thinking about it, most itches go away fairly soon. A few are more insistent, and do not go away as easily; I have yet to find a solution for those.

You can and should practice mindfulness of feelings [sensations]

You should also develop perception of drawbacks;

And what is the perception of drawbacks? It’s when a mendicant has gone to a wilderness, or to the root of a tree, or to an empty hut, and reflects like this: ‘This body has much suffering and many drawbacks. For this body is beset with many kinds of affliction, such as the following. Diseases of the eye, inner ear, nose, tongue, body, head, outer ear, mouth, teeth, and lips. Cough, asthma, catarrh, inflammation, fever, stomach ache, fainting, dysentery, gastric pain, cholera, leprosy, boils, eczema, tuberculosis, epilepsy, herpes, itch, scabs, smallpox, scabies, hemorrhage, diabetes, piles, pimples, and ulcers. Afflictions stemming from disorders of bile, phlegm, wind, or their conjunction. Afflictions caused by change in weather, by not taking care of yourself, by overexertion, or as the result of past deeds. Cold, heat, hunger, thirst, defecation, and urination.’ And so they meditate observing drawbacks in this body. This is called the perception of drawbacks. https://suttacentral.net/an10.60/en/sujato

This condition has it's drawbacks but i think that it also has it's positives in that it can make one a bit more loathsome and serious.

I think in general one can replace loathsomeness by equanimity and endure the sensations. Afaik there is no trick or technique to it other than a comprehensive development of the faculties.

Also obv try to figure out what causes the itching and see if you can reduce it to a min.

Here's the canonical answer:

In this way he dwells contemplating feelings in feelings internally, or dwells contemplating feelings in feelings externally, or dwells contemplating feelings in feelings [both] internally and externally; or dwells contemplating in feelings [their] nature of arising, or dwells contemplating in feelings [their] nature of vanishing, or dwells contemplating in feelings [their] nature of [both] arising and vanishing. Or else his mindfulness that ‘there are feelings’ is established simply to the extent necessary for bare knowledge, for repeated mindfulness. And he dwells independent, and does not cling to anything in the world. Thus also, monks, a monk dwells contemplating feelings in feelings. (Satipaṭṭhāna Sutta, MN10 translated by Aggacitta Bhikkhu)

Take note though that feelings here does not refer to the itch, but how you feel about it.