string - Split string in WiX include file (WXI)

Question

I am trying to alter a variable defined by referencing a project: $(var.PROJECTTITLE).Targetdir is called in my Product.wxs

PROJECTTITLE is of the form company.product.customerAcronym and I would like to be able to change the customerAcronym part dynamically. So basically the best solution imo would be to

1. define a new variable that holds the full targetdir
2. split that new variable based on the dot
3. replace the customerAcronym with the selected one (another defined variable used everywhere else)

Any insights on how to do this?