Thats about it in a nutshell. Get to border early, cross border, 1-2 hours hopefully, busses to Liberia on CR side depart every 30 minutes and take 2 hours to Liberia... From Liberia, its 3 hours to Monteverde, Santa Elena, but nothing direct, so you need to either incorporate a shuttle from Liberia or get off bus at on Pan Am turn off, and catch another bus or hitch...
No easy way...
The cloudforest this time of year in rainy season can be a tad wet, chilly and almost cold at night, and muddy/mucky/misty and messy...
http://thebusschedule.com/
You might want to get to Rivas, then taxi hire to border too. Are you going to Ometepe? I would go there before Monteverde any day of year, or 4 days...its magical and far less touristy...it would be much easier too, and also if going to border after Ometepe, its just 1 hour boat to San Jorge, then taxi hire to border, or just bus to Rivas and bus to border, but thats dragging things out with 2 kids in tow...