As long as the lath and plaster wall is sounds there is no problem with having it around a bath/shower.
Anyway, back to Fallout's issue. Yes, you can try cutting out a section of the lath and plaster down the wall, but it will likely make a mess of the wall. Once you start messing with L&P the plaster can come away all over the shop around where you are working from the vibrations from cutting through the laths (best tool for it is probably a multi function tool).
Afterwards you would need to patch the hole with plasterboard, and fill/patch plaster it all smooth an level.
If there aren't any noggins in the way, I would suggest just making a hole at the bottom, and one where you fit the shower fitting, and then using plastic pipe and poking it up the wall. A lot less making good.
Other possible suggestions:
1. If you are just tiling inside the shower area, cover the whole area with aquapanel, screwed to the wall. It will make the tiles proud of the wall by another 10mm, but you could use trim at the edge of the shower enclosure to hide it.
2. Dryline the wall with moisture resistant plasterboard.
I'm basically doing that on one wall on my current bathroom refurb. It's L&P, it's pretty uneven, esp. down one bottom corner where it sort of curves out. If I take the tiles off the tiled bit, it will be a mess wand will need replastering etc. etc. Though I'm not going to dryline it as such with battens , which will be a faffy job on that wall to get them level. I'm just building a stud wall effectively right against the existing wall (using 2x3 CLS timbers on edge to keep the depth down as much as possible).
It will give me space for running pipes for the bath filler wallspout, and easy wiring for some wall lights we want to put up, aand wasy to fix things to. And I will have a nice flat wall for tiling. It's lots of work, but bathroom last for a long time, it's worth getting it right.