north_alabama,
You've got the right idea. I've seen where Lobelia cardinalis and Lobelia siphilitica (sp?) will cross in nature. So, why not try laxiflora.
Anyway, here's something I'd suggest. I'd apply pollen repeatedly over the course of several days to a week, because I don't know when the "receiver thingee" becomes receptive in Lobelias. Usually it becomes sticky; so, you could use that as a sign that it's ready. Also, if you want to be more sure that what you're doing is working; you might want to try removing the "pollen thingees" from the mother flowers before they've released any pollen. This'll prevent self-pollination. Of course you've got to find some way to keep bees from getting to the flowers afterwards -- if you're worried about that kind of thing. And you don't have to be. I've gotten many hybrids of things just by moving pollen around and then sorting out the hybrids from the normal.
Rereading this just made me think of something. You do know that you'll have to plant the resulting seeds?? Because, that's what'll grow up to be the hybrids. I forget that sometimes, people might not be thinking that it works that way. I know some beginners confuse hybridizing with grafting, and think that transferring pollen changes the parent plants in some way.
Well, good luck with the Lobelias and try some other pollen-moving if you get a chance. It's great fun to see what comes from it.
Take care, Tom

Thanks Tom,

It should be fun. I also have multiple cuphea species, and multiple salvia species. Hopefully they'll make good fodder as well.