Hi and welcome.
Honda only allows lower LATCH anchor installations in seating positions with a dedicated set of lower LATCH anchors and doesn't allow you to "borrow" a lower LATCH anchor from each captain's chair to do a center LATCH installation on the Plus One seat. The Plus One seat also lacks a top tether anchor for forward facing installations, but every other rear seating position in the '10 Odyssey is equipped with a top tether anchor to my knowledge. You'll need to install with the vehicle seatbelt in the Plus One seat, or install on a captain's chair if you wish to use LATCH in the van's second row. If you prefer a LATCH installation in the second row center, I believe the '10 Ody has the option of moving the second row passenger side captain's chair over to the second row center. A lower LATCH anchor installation isn't technically safer than a seatbelt installation or vice versa, for what it's worth - what matters most is achieving a proper installation with less than 1" of movement at the carseat's belt path using an allowed installation method.
If you're installing the Blvd. rear facing (the optimal, safest way to travel for children until they reach the maximum rear facing capacity of the convertible carseat, and we can provide more info. on the benefits of doing so if you like
) and looking for guidance on where to tether the Blvd. rear facing using its included rear facing D-ring tether connector strap to create a rear facing tether anchor point in the Odyssey, there's a helpful article with Odyssey specific suggestions at:
http://www.car-seat.org/showthread.php?t=9902
There are a couple more points to be aware of with installations in the '10 Ody that you might already know about, but I'm going to mention just in case and because we have lurkers/google searchers who might benefit from viewing this thread.
In models equipped with advanced airbags, such as your '10 Ody, Honda doesn't allowing a rear facing carseat to touch the front passenger seatback due to potential interference with the sensors for the advanced front airbags. Also, all Honda vehicles have a 40 lb. child weight limit for lower LATCH anchor installations.