RTC & JAZZ Build Engine auto build with precondition

You could potentially do that by a custom follow up action. See the Rational Team Concert Extensions Workshop which describes this in detail for changing a work item state. You would want a follow up action on delivery. This means that the operation ID would need to be changed.

https://rsjazz.wordpress.com/2012/11/01/restrict-delivery-of-changesets-to-workitem-types-advisordelivery-of-changesets-associated-to-wrong-work-item-types-advisor/ shows an advisor (pre-condition) it uses a slightly different extension point, however except the interface it implements the code can be used and the operation ID you look for (Extension Points and Operation ID’s) is the right one and you could pull the build related code from the workshop.

Please note, developing extensions requires some skills and I would suggest to start here: https://rsjazz.wordpress.com/2013/02/28/setting-up-rational-team-concert-for-api-development/ and carefully perform the workshop before going into your own extension. carefully look into the examples given on https://rsjazz.wordpress.com/ and in general the internet (e.g. some code examples can be found on Jazz.net and on stackoverflow).