Change finish page run parameters depending on command line

I have created a installation setup which requires finish page run parameters. So i am using

!define MUI_FINISHPAGE_RUN_PARAMETERS "?/?Setup?/?Common?/?"

But if i pass a command line to a setup then this run parameters should be changed. how it can be done? I know command line parameters can be accessed using GetParameters. But how to change MUI_FINISHPAGE_RUN_PARAMETERS depending on command line passed to setup?

Define it as a variable and set the value before the finish page shows.