Winny run for a short few weeks is not going to be that harmful to the liver. I ran a rather ridiculous amount of orals as well as a super high dose of letrozole (to try and get rid of a bit of existing gyno) and then halotestin at the end in the run up to my show. My liver values at the end (which should have been sky high) were only elevated a few points; and with some good nutrition and silymarin everything was back to normal after 2 more months.
Silymarin (from milk thistle) does, in my opinion, work. And will help with liver support. I have also heard from a very intelligent guy that coffee, of all things, is a fantastic agent for taking care of the liver.
All that said, if you are really worried about it, why not buy a single vial of masteron and start using it two to three weeks out. Then you can drop your other compounds and go in nice and dry and not have to worry about liver damage (which, for the record, I think is rather over-rated).