Create custom Bootstrapper Application

[AntonyNifosi]

I have a solution where I got 2 projects. One generating a package (.msi), one generating a bundle (.exe installer) with the MSI and other MSI / EXE.
I would like to be able to choose, when I am using the EXE installer, which package to install with checkbox for example. I didn't find anything to do it ?
Do I have to do my own bootstrapper to achieve this or is it possible by only wix stuff or maybe XML (I saw that themes for installer are XML files).

[AntonyNifosi]

Anyone?

[AntonyNifosi]

It seems I have to write my own bootstrapper, is there any doc to explain how achieve it ? In last wix version (5.0.0)