I'm learning Hō-ló myself (台語, a.k.a. "Taiwanese Hokkien", among other things, Amoy, Hoklo, Min-Nan, Taiwanese, 廈門話, 河洛, 臺灣話, 閩南語 福建, 鶴佬... and a few other names, too)...
...and I've started a Google Group to bring together the small number of foreigners studying the language...
...so that students of the language can meet one-another, and, potentially, meet native speakers of the language who would be interested in answering questions or teaching the language.
The name of the Google Group is exactly the same as the title of this message, "Learning Hō-ló (台語, 臺灣話)", but the URL pertaining to it is just "learning-ho-lo".
Unfortunately, it seems that Google is currently in the process of redesigning its groups system, and there are some technical annoyances. If you can't join directly by clicking on that link, I can only encourage you to keep trying, as the group does exist (and is working) but the system used to apply to join seems to be quite frustrating.
You can see some of my own work on the language as it gets added to my blog (I'm currently working on a series of modestly-illustrated vocabularies), e.g., http://a-bas-le-ciel.blogspot.ca/2012/0 ... fruit.html
(As you can guess from that illustration, this isn't the first language I've worked on in Asia...)
BTW, I've seen the complaints (posted here on Forumosa) that there have hardly been any new textbooks to compete with the Maryknoll materials; in fact, a new textbook was published in 2010, but it seems that almost nobody noticed in Taiwan (perhaps because it was published in Europe?). I wrote my own informal review of the book, partly just to let people know that it exists: