Possible to Have Non-WP Script Create Pages?

Is it possible to have a non-WP script, which is not in the directory, create pages dynamically through the WP system with comments enabled? Anyone in the “contributor” user role needs to be able to do this, and WP must be able to handle a 4-5 figure amount of pages. Would that be overload?

(I’m trying to integrate a custom application—which is done—but also add a comments feature to each page a member creates.)

Thanks!