The Salesforce to Marketo sync is an implicit process, not exposed to any API.
The sync starts automatically in fixed intervals after the last sync is complete.
The default value is five minutes.
Marketo to Salesforce sync has two methods:
- Munchkin API : associateLead
- SOAP API : syncLead and syncMultipleLeads
There is no tangible benefit overriding the Salesforce to Marketo sync.
I would suggest posting a feature/enahncement request through Ideas if you can foresee any.