It's not totaly clear what you realy want to do but i give it a go.
First you have to assign the net to the plane on the corresponding layer. You can do this by SETUP-LAYER DEFINITION...
Set the PLANE TYPE on SPLIT/MIXED (or CAM PLANE) and press ASSIGN NETS. Add the desired net to ASSIGNED NETS.
Now comes the part that i don't understand in your question but i give three solutions that may help.
1- When you draw the outline of the plane, be sure the pin you want to connect is part of it.
2- When the pin is outside the plane area, route from the pin to an other pin or track inside the plane area. There will be a pop-up window about a trace loop and select here CREATE LOOP. When this trace is unrouted by whatever, the connection is gone and you must remember that you once made an extra connection.
3- Draw a small copper line inside the plane area and assign the copper to the net. Now you can route from this line to the pin.