He can drink it, but you get a lot more absorbsion in the colon and large intenstine by bypassing the stomach. Just have him stick a small funnel up his ass (note: be sure to coat the tip with k-y), and pour it in for him.
Now, the important part is that he has to hold it in there for at least 30 minutes for optimal absorbsion, so make sure he does not take a dump for at least 30 minutes after his winstrol enima.
This is by far the most effective method, you get an absorbsion rate at least 50% higher than drinking or injecting.