Telefunken U373a - Input and output controls?

[UffeK]

I can see that this guy has added an input and output control for his U373a compressor.
Any idea how to do this the best possible way?

http://www.ebay.com/itm/VELVET-AUDIO-Telefunken-U373a-Stereo-Compressor-Limiter-21347-/171792067224

 

Here is the original diagram:
http://audio.kubarth.com/rundfunk/getfile.cgi?f=%3A%2C30X-S4Q-38Q%2C5%5DU%2BW1A8E%5DU%2CS%3CS82YG%3A68%60%0A

Thanks

 

[mro]

I guess adding a dual lineamp such as v372D on the input would work well and maybe just an attenuator on the output. Should be the easiest way to add more controls to your limiter