Yes, хуй can also be used with в instead of на, so the ‘on’ is better than ‘to’. However, we could combine the two to be even more accurate and imply the motion

Yes, хуй can also be used with в instead of на, so the ‘on’ is better than ‘to’. However, we could combine the two to be even more accurate and imply the motion: ‘go onto dick’. We can also improve the translation by adding an article: ‘go onto a dick’. Alternatively, we can make a slightly more idiomatic translation by fiddling a bit with the verb: “get on a dick” is my favourite version of this, conveying the meaning well without sacrificing too much accuracy.