Hi @berry.lejeune & @Michael.Navara. There is actually a fairly simple iLogic line of code for importing & exporting the parameters to & from XML file. See the following two lines:
iLogicVb.Automation.ParametersXmlSave(oDoc, XMLFileName, XmlSaveOption.All)
iLogicVb.Automation.ParametersXmlLoad(oDoc, XMLFileName)
Of course, in this example the oDoc variable, and the XMLFileName variable would have to be declared and their values set before that point, and there are three options to the XmlSaveOption, which is an Enum (All, KeysOnly, & None).
Edit: Here are the online help links for those two methods: ParametersXmlSave & ParametersXmlLoad
The documentation also says that you should supply the full file path of the XML file, not just its name, in case that was not clear. And logic would suggest that the document you supply as the first input variable should be the Inventor document that you want the parameters to be imported into, or exported from. And if setting the XMLSaveOption to KeysOnly when exporting, make sure you check the checkbox for those parameters under the 'Export Parameter' column, so they will be recognized, before attempting to export them by code.
Wesley Crihfield

(Not an Autodesk Employee)