Hello looking a translation into gaelic for Here's to cheating, stealing, fighting, and drinking and also if you must drink, may you drink with me, My Brothers in Arms.

Thank you. Cathal Tierney

Not sure how to say "here's to", maybe "molaim".

Molaim rógaireacht; goid; troid; agus ólachán. Agus freisin má chaitheann tú ól, ól liomsa, mó chomradaithe sa troid.

(I'mnot sure how to say Brothers in Arms either.)

Not sure how traditional it is in Irish, but for "brother-in-arms", De Bhaldraithe has "compánach cogaidh", and for the expression "Here's to ...!" it has "Seo sláinte + [gen.]", although I'm not sure whether that works for drinking to the health of something inanimate, so Bríd's idea of using molaim ("I praise/recommend") might be better. In case seo sláinte does work, then building on what Bríd said, perhaps the following would work (but definitely wait for others to comment on or correct my grammar):

Seo sláinte rógaireachta, goidte, troda, 's ólacháin; agus lena chois sin, má chaitheann sibh ól, go n-óla sibh liomsa, a chompánaigh cogaidh.
Here's to cheating, stealing, fighting, and drinking; and also, if you must drink, may you drink with me, My Brothers in Arms.

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I'm not a native (or entirely fluent) speaker, so be sure to wait for confirmations/corrections, especially for tattoos.

Good catch - yes it should be plural "sibh".