Creating custom VM for OpenWrt in VirtualBox

I followed this guide for creating an OpenWrt VM and was successfully able to spin up a machine. What I would like however is to possibly be able to create a machine using customized architecture using my own bin file I was able to convert a factory bin to a vdi in a similar way as in the guide and used the same OS setup (Linux 2.6) However when I try to use the machine it fails to boot unlike before I'm not sure if it is possible to create a VM in Vbox this way, but it would save a lot of time in testing before moving to the actual hardware. Even having limited functionality would be immensely time saving