Create a free, second Steam account. Use a Visa gift card or a free game key to "activate" the account (some games require a $5 spend to unlock Workshop access). Use that account to subscribe to mods, then copy the files from your steamapps\workshop\content\[AppID]\ folder. This keeps your main account safe.
Have you used "O" style downloaders? Share your experiences (and horror stories) in the comments below. Steam Workshop Downloader O