I don't think this will work. There is an existing help article (
https://community.marketo.com/MarketoArticle?id=kA050000000KzZKCA0) that discusses this approach - but only for separating values - not name/value pairs which is where the two colons are used. So in this case, the three vertical lines would be used to replace the comma.
Here's an example of the name/value pair approach we're using:
Please Select::,Executive Officer::CXO,Senior Executive::Executive- or -
Please Select::,Argentina::AR,Australia::AU,Austria::AT