To ascertain if you are prepared to take ST 412/512 without having had ST 411/511 at Oregon State University, you will need to have a look at the textbook, The Statistical Sleuth, 3rd Ed. by Ramsey and Schafer, available at course reserves at the Valley Library. ST 411/511 covers the first eight chapters of this book. Even if you are familiar with the topics covered, this book has a different approach and different notation than most texts. In particular, you should be comfortable translating the results of hypothesis tests and confidence intervals into non-technical statistical conclusions, as illustrated in The Statistical Sleuth. You should also be familiar with what the book refers to as "scope of inference."
All data analysis in ST 411/511 is done using R within RStudio, so you will be expected to be reasonably familiar with this software. R is available at no cost (http://cran.r-project.org). RStudio is also free (https://rstudio.com/products/rstudio/download/).
If you wish to register for ST 412/512 after you have assessed your preparedness, please email me at madsenl@oregonstate.edu with your student ID number and the lab time you want. I will forward to our office staff to process the override.