Need to know to which Australian state?
https://www.records.nsw.gov.au/archives/collections-and-research/guides-and-indexes/assisted-immigrants-digital-shipping-lists
Has 3 journeys on HOTSPUR, none in 1857.
http://www.theshipslist.com/ships/australia/1857-1858.shtml
Has just 1 HOTSPUR to Victoria. Ships' manifestos vary: The may state county or origin or just "Ireland".
Date of Departure 2 July 1857 with 489 "souls"
Date of Arrival 12 October 1857 with 485 "souls" (4 d. at sea)
This data from Appendix No. 9 Victoria
Return of Ships and Emigrants dispatched by Public Funds to Victoria, in 1856, 1857, and up to the 31st March 1858.
I suggest you contact major Lbrary or Vic. Govt. Records of Vic.PRO (sorry, not familiar with Vic)
The chances of a Manifesto informing the place of prayer is remote.
Alternative is to know: Did they come with children? If so, search the NLI (free online) for the baptism record(s) of child(ren). The last Parish, pre-departure is probably closest for an educated guess.
Monteagle Project, after Lord Monteagle, has many availabe references. However, again the fine detail of place of prayer is remote.
https://www.nla.gov.au/sites/default/files/d7_files/blogs/m_976_lord_monteagle.pdf
TROVE (NLA) can help searching https://trove.nla.gov.au/work/11760073?q&versionId=13848387+50748344
http://home.alphalink.com.au/~datatree/poverty1.htm Some light may be here:"
- Danaher Mary 95-6 (on next line) Danaher Mary see O'Brien and from there
- O'Brien Mary nee Danaher 181, 185, 211
- NB: "INDEX Only the index is available. If you wish to purchase this book you will need to write to Crossing Press, PO Box 1137, Darlinghurst, NSW Australia 2010"
Alternatively, search Parish wedding John O'Brien & Mary Danaher, with approx. date range. Hopefully there won't be too many! Rule of thumb, RC marriages occurred at the Bride's home church. Only downside, is Danaher may have been from another Irish county.
This book "POVERTY TO PROMISE" By Dr Christopher O'Mahoney and Valerie Thompson appears to answer many genealogists' prayers. So maybe check your local most prominent library.
I just did a check of RC marriages 1847 +/- 10 years for a Mary Danaher & John O'Brien, in all counties with various alternative spelling and found nothing at all. Best suggestion is access to the "POVERTY TO PROMISE" book.
Hope something here is of use.