EDIT: The post below is now redundant, since the OctaneRender for Modo plugin automatically support camera projection texture locator.
I was asked it was possible to setup camera projection textures in OctaneRender for Modo. The answer is "Yes", although at the moment it requires some manual processing. To set this up, add an Octane Override for the Modo material and then open the Viewport.
1) Add an Octane Perspective Projection node and connect it to the Projection pin of the Octane RGB Image node
2) Select the Octane Transform Value connected to the new Octane Perspective Projection node, and manual enter the current Render Camera transform values. You should notice the texture is now projected according to the current camera position in the OctaneRender Viewport
3) Add an Octane 3D Transform node and connect it to the Transform pin of the Octane RGB Image node.
4) Select the Octane Float Value connected to the Scale pin of the new Octane 3D Transform. Click the Gang edit control until it is set to "=", and then slide one of the value to get the texture size you need. You can also adjust the Translation to adjust the position of the projected texture.
I plan on semi-automated the above where possible in the next release. In particular, adding the ability to connect the Modo camera transform node to the Octane Transform node would be great.