Prolly easiest for the do-it-yourselfer to screw down the particle board. 4 and 8* is way plenty. Try to run the screws into structure (read joists) and either run perpendicular or offset the particle board in relation to the existing floor sheathing. IOW, avoid lining up joints from one system to another.
The above is about fighting squeaks, in fact go on a squeak hunt before you flop down the particle board.

Follow the manufacturer's recommendations on the flooring install.

* Fastener schedule:
(approx) 4" on the perimeter (ea sheet) and 8" in the field of (ea sheet) of particle board.