1 voteIdan Yona commented
not sure about VSAE, but it actually works in raw xml, there is actually an paid MP that works that way (the OZSoft SAP MP), however a word of cation almost every tool\ extention \additional mp and so on relies on the fact that alertname to alert rule is a one to one relationship, breaking that best practice can cause several issues in the future such as reports mismatches, notification managers misalignment and so on.
if your issue is the subject line in mail notification, i would suggest doing the customization there using custom alert parameters
7 votesIdan Yona commented
you can accomplish that in a dev environment by installing the VSAE on a gateway or management server, unlike the old authoring console VSAE uses the underlying binaries to execute the simulator (that is you would normally install an agent on your dev machine)
so as soon as your binaries include the *NIX modules (when installing an MS or GW) you can run the simulator on them, i tested it only on an MS but the logic should hold for GW as well