I have both been playing a 5 string for ever and growing up in an Irish trad home so here is what I do, cheap cheeful and a giggle especially if one happens to transform in a Bluegrass jam!

I tune the B string up to D, the D up to E. Now to get most of the rest of the notes available in GDAE I tune the low D down to C.

Capo on the second fret OR if you have an older Banjo you may low tune it to start, then capo to the fret yeilding DAEF# tuning.

The 5th String is tuned up to A.

Why this tuning is better suited to and easier needs little explanation since Irish trad is most often set for the Tin Whistle, lowest note D, and highest note in high parts maxes out at B'.

The beauty of it is that one uses the F# string for these higher notes thus not ever having to reach for that irriating B'.

Since the action will be affected by this new setup I found using a Calfskin head to be the best solution, also and surprisingly it sounds FAR better for early Bluegrass picking as well. The only drawback is that on occasion I have to fiddle with the tension to get good bounce in Plectrum style.

I do not play Jazz or Classical so I have no idea what that would be like.

Strings can be a pain here, I have used 'Vega' Lights for ever and tried but did not like the Medium gauge but again that is individual taste. The local store here sells these sets by C F Martin & Co for around seven bucks.

Chording can be an new learning experience for those into this kind of thing but I found it easy and intuitive to construct Major - Minor and a couple of Modal for singing to.

The moral of this posting is that with a little care and preparation a student can adapt a 5 String to Irish Tenor use with very little expense, and as any yard sale shopper knows 5 strings are not that rare these days, in fact ther's a surplus of them out here at this time. I just now wonder if this is result of the false idea that one MUST use a regular 4 string to play Irish trad in the Tenor Plectrum style?

A word of good advice from one knowing the pain of doing it wrong! From day use a Tutor such as Sully's Irish Trad for Banjo. Why? The direction of Picking is not simply UP then DOWN on the next note. It sometimes goes two notes in the same direction for effect and it is this that makes the style so intoxicating. If I say that every time one crosses to the next string going down towards the floor - ie up in pitch - then the pick must follow the last Down with another Down I may be misleading the reader; however there are lots of tunes that do just that!