Parece que a documentação é esparsa, mas o VirtualBox tem suporte a LPT a partir de 4.2.
--lptmode<1-N> <Device>Specifies the Device Name of the parallel port that the Parallel Port feature will be using. Use this before--lpt. This feature is host operating system specific.
--lpt<1-N> <I/O base> <IRQ>Specifies the I/O address of the parallel port and the IRQ number that the Parallel Port feature will be using. Use this after--lptmod. I/O base address and IRQ are the values that guest sees i.e. the values avalable under guest Device Manager.
Isso também parece útil:
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Ativando e configurando portas paralelas (LPTx)