Symmetricom XLi : Oscillator Configuration

[comsec22]

How to upgrade the internal reference oscillator, beside to add a better OCXO (or a rubidium) instead of the standard TCVCXO ?
According to the manual it's a matter of hardware configuration, but how to switch from one to another ?
Unless to use J3 as external reference..

Thank You

[testpoint1]

How to upgrade the internal reference oscillator, beside to add a better OCXO (or a rubidium) instead of the standard TCVCXO ?
According to the manual it's a matter of hardware configuration, but how to switch from one to another ?
Unless to use J3 as external reference..

Thank You

for the hardware, it is easy to change one, but, no command can modify it.