The texture the wire of tripmine uses is in models \ weapons2 \ tripmine \ wire_blue.tga in silent-0.8.2.pk3
You can extract wire_blue.tga and modify it to your liking, change eg blue for a more discreet gray.
Never modify the texture of wire_blue.tga in silent-0.8.2.pk3
Create a small pk3 and name it as you like but add a "z_" at the begginig of the name,pk3 (eg. z_name.pk3); within the pk3 create the folder structure models \ weapons2 \ tripmine \ wire_blue.tga where wire_blue.tga will now be your version.
Climb this small pk3 the silent folder on your server.
It is true that it is visible to kilometers ..