Question I need some help! Seriously...

Well~

Even though I could grasp the original meaning of the passage in Japanese, it is myself who couldn't interpret it to common English... Hence I am so sorry for this.

 

あ、じゃあ雄二さ、気持ちしたいって程度におしっこしたくなれって念じてみてくれよ
"OK, so, Yuuji, try thinking 'Need to go pee!' really hard as if you want to feel [you need to go]."

〜（という）程度に followed by 思う［考える／念じる］means to "think as if 〜 (is the case)" or "think it’s merely (the case that) 〜." And what comes before the 程度に can be either a literal quote or just be a description of the thought.

 

[May be the ability still shared even if your mind is divided?
Ah, say Yuuji , try imagine yourself you wanna pee so much.]

it is just he is talking to himself (figuring about his ability himself),so informal tone might suit the mood.
something like that. i don't know about eji & biji status tho (age and big/beige status dunno)

意識も分かれてるのに能力は共有ってか？　
あ、じゃあ雄二さ、気持ちしたいって程度におしっこしたくなれって念じてみてくれよ