A really interesting website and I'm inclined to agree that St Patrick's cross is hard to link with the vikings. As the original is lost, we'll never know for sure, but this is a nice piece of detective work which sheds light on the cult of St Patrick in Liverpool and the development of the port's connections with Ireland.
I have just been looking at your site after seeing your post on My Liverpool. Very interesting reading. I remember years ago reading a book called 'Ancient Meols' which seemed to indicate that Hoylake was the main port in earlier times. Also that Hilbre Island was much, much larger than present day, that there was a fresh water spring on it and it had a small monastic community. Given this information and the fact that there was a ferry run by monks at Birkenhead, it is quite feasible that there could have been a religious route through Liverpool.
I hope this information is of some help and I hope you have more success with your research. I will keep looking at your site from time to time to watch the progress.