Can I get my Elder Scrolls IV mods through my Mac to to my PC Upstairs though a USP drive? If not is there any way, only my mac can have online connection. And is it likely that I can just setup and play there? I have PC version of Elder Scrolls and I want to update it with mods.

You should be able to. Do you have wireless in your home?

Yes but to my mac only.

yes but to my mac only.

Then you might wish to invest in a usb wireless. They aren't that expensive and you can just plug it into your PC when needed or leave it there all the time.

Ref

Search Results for usb wireless at TigerDirect.com (http://www.tigerdirect.com/applications/SearchTools/search.asp?keywords=usb+wireless)