I've made two 10 gallon batches of L. Plantarum (swanson) kettle sours that have turned out great. @drgonzo2k2 sounds like he's got more experience than I do, but I'll pitch in my 2 cents.
Both times I made 2L starters (for 10 gallons) using about 50/50 DME/Sugar, and covered the starter with cling wrap to prevent oxygen ingress. I mashed & sparged as normal for a 1040-50ish 80/20 pils/wheat recipe, then brought it up to a boil. Chill down to 100*F ish, pitch the lacto starter, then let it ride and cool down naturally over the course of about 48 hours. After the 48 hour mark, bring the wort up to a boil, and if you want to add boil hops just add them at the end of the boil. Some people will mention success with "no boil" recipes but I've personally tasted some with massive DMS (cooked corn) character....it may depend on your palate. I have no issue doing a full 60 minute boil just to be safe. No hops is totally fine....you don't want to compete the acidity with bitterness. Also, keep in mind if you taste the wort that's been acidified with Lacto will certainly taste MUCH more sour once fermented. Wort that hasn't been fermented by yeast yet will have a big sweetness to cancel/balance out the acidity of the lacto.
Ferment with a relatively clean ale yeast ideally....though I've used WLP644 Sacch "Brett" Trois with success as well. Simple kettle sours like this are KILLER with fruit additions in the secondary. I've done Pluots in batch and Apricots in another with success. My Pluot kettle sour keg kicked at NHC club night in Baltimore this year. If you want to dry hop, go for that too, but shoot for new-school fruity/citrusy hops to compliment the flavors you get from the lacto. I've found the L. Plantarum capsules give you a really nice pineapple/citrus character to the acidity.
Cheers