No matter how you look at it, I still can't do it.
1) However you look at it, you're doing too much.
「いくらなんでもそれはやりすぎでしょ。」
2) There is no way I can do that.
「いくらなんでもできないよ。」
3) No matter how you look at it, I still can't do it.
「いくらなんでもやっぱり無理だよ。」
「いくらなんでも」は
however you look at it
there is no way I can do that
no matter how you look at it
などを使って表現できます。
ご参考になれば幸いです!