Yes - you'll be pleased to know it's easy.
1. Open two Finder windows; one containing your Virtual Acorn stuff and the other Documents.
2. Drag the Hard Disc 4 directory into Documents.
3. Open a Terminal window (it's in Applications -> Utilities in case you've never used it before).
4. Type in the following:
cd /Applications/VirtualAcorn/VirtualRPC-AdjustSA
ln -s /Users/username/Documents/HardDisc4 ./HardDisc4
where ln is the first and third letters of the word link (the l is not a number 1
) and username is your username.
Load Virtual Acorn and your hard disc will appear as normal, but will be located in Documents.
You can use ln for other useful things - e.g., if you have RPCEmu running so you can use RO5 applications, they can share an Applications directory. I've used ln to access Google Drive from VRPC. That way I can save a Risc OS document on my iMac and access it on my MacBook (both of which have VRPC installed).