Change homing between immediate and home-switch

Is there a good way to alter the home sequence while axis is running? I want to add a button to my glade panel that can home 4 of my 5 axes, and then leave the 5th to do an immediate home. BUT - I want to keep the usual axis home button working. This way I can home my 5th axis properly when I start up, log the axis position (rotary position) continually, and then use the logged position to perform an immediate home when I restart the program.

I need to do this to avoid damaging the workpiece, since another part of the machine is connected to the rotary axis during the program.

Both of your suggestions sound fine - but what I have difficulty with isn't starting the homing procedure (from either hal or python).

What I have to do is alter the homing behaviour of the 5th axis, as defined by the INI file, after the INI file has been loaded.

I have a home switch that I want to use for the B axis (the 5th axis), but I only want to use it some of the time.

The other part of the time, I want to be able to home immediately, and specify the position value at which the home is set.

Picture this - I have a rotary axis that is interacting with some material. When I start the program for the first time, I attach the material to the axis. Then, I want to stop the axis, shut down LinuxCNC, and leave everything like that for a while. At some point, I return to the project, and I want to resume where I left off. I load the last remembered axis position from a file, set the home position to that value, and declare axis B to 'be homed' at the current position (so I simply update the software position, I don't change the actual physical position). This way I don't have to disengage the axis from the material in order to home it. This might require mucking around with how INI parameters are fed to halui and axis. Any ideas?