Unidirectional sync. from SFDC to Marketo

Hello,

I am setting up Marketo and SFDC integration. I want to set-up a unidirectional sync. i.e- sync from SFDC to Marketo only but not vice versa. I do not want the SFDC fields to update when there is a change in the corresponding Marketo field. I understand the conventional integration steps but this is a unique requirement. Can anyone recommend the steps?