Need help with purging...

[Rcfiddy1]

Finished building my ercf for my Trident but I am struggling with the purge after a filament load. to get a clean filament i need to extrude around 40-50mm of filament but dont want to use a purge block. I am running different materials for supports and if I do a purge block it tends to fail. I dont want to use blobifier since I have fan units on both sides of bed and also it looks like its not for a trident. I just want to park nozzle next to my brush cleaner, extrude 50mm after loading, than do a wipe and resume. I am not sure where to try and insert that code.