You have to distinguish between the CAN 2.0 layer and the CanOpen protocol stack. The CAN 2.0 communication layer has a multi master topology, but CanOpen ist a strict master slave protocol in which only one master can be in the network.

If you only want to exchange PDOs, you don't actually need a CanOpen protocol stack, you need the Cob-Ids of the supported PDOS and the format of the 8 data bytes. With these information you can exchange the appropriate CAN 2.0 messages

However, if you want to configure a CanOpen device (slave), you need a CanOpen master. A Can-Slave software package cannot be easily converted into a CanOpen Master. It has a completely different mirror-image structure.