It Works
In BC, zoom into the area where you want the alert.
Select "new waypoint" (arrow with little square) then click where you want the proximity alert.
Repeat for any others you want.
In the left pane, select one of your new waypoints. (double click)
In the sub window, select the Properties tab. In the Proximity field enter a value. 0 = 400 mtrs or the mile equivalent. I use 200. You have to enter the distance as .2 km and then BC will make it 200m - the same procedure if you use miles.
I also changed the Display field to a red square -
In the Notes tab, give it a name.
Close the sub window.
In the left pane, high-light and waypoints you want to process (CTRL + select)
Click - File > Export > Export Selection - save it in a directory with "SPECS" in the name. I used SPECS_POI_Announce and the file name the same as.
Fire up POILoader to send it to the XT. I used the same name for the GPI file as the GPX file.
Fire up the XT > Settings > Driver Assitance > Proximity Alerts > Alerts > Tick Custom POIs
It works. I had it set to 400m at first, but one of the PA's was at the end of a U shaped piece of road and it did the alert at 400m as the crow flies.
It gives 3 bongs in quick succession. Not found a way to change that.
It works without being on a Route. Not tried it while navigating.