Do you have any clues as to an approximate year of birth for your Timothy ?
I presume it would be 1820s or earlier if he married in 1842..
There are a couple of difficulties with getting started on this search unfortunately :
1. 'Dublin' can mean the city suburbs or county, so quite a few parishes.. and several denomination e.g. Catholic, Church of Ireland etc
2. 1820s is quite early for Irish records - not all parishes have records back that far, particularly rural Catholic parishes
3. without a more precise location and/or some family details it will be difficult to confirm or rule out any potential matches.
4. The surname 'Roane' is probably a spelling variant - possibly of Ruane or Roan, Rowan etc
A quick check of Catholic records for Dublin city and county for possible baptisms of a Timothy Ruane/Roane or similar 1825 +-20 years is not showing any promising matches. A search of the surviving Church of Ireland records for Dublin city is showing a few early records with the spelling as Roane - but nothing promising that I have located for your Timothy.
Have you any additional details on family or parents for Timothy ? e.g. parents are sometimes mentioned on death certs, and death notice/obit may mention siblings etc