I have been working on a texture pack for a plugin called slimefun. In this plugin there is an armor set called "Slime Armor". As the name says its made out of slime. So properly portray this armor i wanted to make the textures translucent. Is this possible using CIT?

Not currently possible as the armor renderer uses cutout blending and as such does not support translucency.
This might be a thing you could do later down the line when the armor cit type will get a rework but I cannot guarantee it.

I think u should use translucent texture to get it. As u draw in argb, u should be able to set opaque as alpha channel.