I think the one you have is also rear facing? But imagine forward facing will be the same as mine. If so yes it is easy,Basically the seatbelt goes through the back the lap belt at the bottom doesn't fit into it anything just sits in front of 2 nobs on either sides, the top part of the seatbelt sits in the red catches , depending on the side that the carseat is on( this is the only fiddle part)
I know that doesn't really make sense but hopefully it will when you have a look at it, but to make it easier to clip the seatbelt in recline the seat to slide it thru, also once its in put your knee into the carseat push it back and tighten the seatbelt as much as you can.
Hope you manage it!! lol