Tap the compressor housing for takeoff point or alternatively you could do so from any point upstream of the turbo. (e.g. intercooler end tank or boost pipe etc)

When looking at the tial wastegate capsule, the lower fittings (i.e. thoses nearest the actual valve body) are the ones can cause the wastegate to open when pressure is applied. If you have removed a turbo with a actuator and internal wastegate, using the lower fittings on the external gate will allow the wastegate to work in exactly the same manner as your old turbo did.

The fittings on the very top of the external wastegate capsule allow you to apply pressure to the wastegate thus increasing boost above the wastegate spring pressure. You won't need to use this function as your boost controller will control the feed pressure to regulate boost.

I can't comment on your boost controller as I do not know the port functions. If for example you were using a bleed valve it would go :

compressor to bleed valve in, bleed valve out to lower side of exteral wastgate capsule. Bleed valve bleed to atmosphere.

Hope that helps.