Patching and Plastering - filling in between rock wall and window frame

We recently bought a house in a warmer clime. It has rock walls and 2x4's for framing the windows. The vertical columns of rock wall do not meet the window frames smoothly, lots of gaps from 0" to 1.5". We would like to cement these 6' vertical gaps, but don't know if cement is really the way to go. Also, is there a chaulking product like cement that could get into the gaps better than trowelling cement?

Advice is welcomed!

There is a product, can't recall the exact name of it, but it's basically mortar in a tube. Works well for small repairs, but can get kinda pricey if you're trying to fill in any significant amount of area. Personally I would suggest you go to your local home center or lumber yard and pick up a bag of mortar mix and a grout bag. It comes in a dry powder form, and just contains portland cement and sand, no aggregate. You add water just like a sack concrete and once you've got it mixed up you put it into the grout bag and then you can squeeze it out into the gaps around the windows. Hope that helps.

Thanks for the advice. We'll cost it out. Hopefully the putty idea will win (much simpler).