The main part of the !Boot sequence that you will be interested in is in !Boot.Choices.Boot.Tasks. In order to open the !Boot sequence you will need to hold down SHIFT while double clicking on the !Boot icon in the HostFS::HardDisc4 window.

The picture above shows you where the important files live.
Do not delete the !DeskCtrl, !MemNow, Alarms, ModeSet, SetDir or SyncClock programs from the !Boot.Choices.Boot.Tasks directory. If you do then you may find that some features of VirtualRPC-SA will no longer work correctly and you will be forced to re-install VirtualRPC-SA.
Your new fonts will now be available in the same font menus as your existing Fonts.
To add a single module to RISC OS follow the sequence shown below:
To add a set of modules contained in a !System folder:
Your new module will now be available.
It is possible that you won't find the exact screen resolution you need for your computer from the available options. In this case you can use the AutoMode configuration tool to generate the correct MDF (Monitor Definition File) for your screen display. To use AutoMode simply click on the AutoMode icon and then enter the required screen resolution. You can select what frame rates the screen mode will have available. The normal choices are 30Hz, 51hz and 75Hz. Clicking on the SAve Updated MDF button will generate the new screen modes and they will become instantly available from both the monitor icon on the RISC OS iconbar and from the Monitor configuration tool.

VRPC manual - draft number 150.001 10th May 2006