This is just like doing a standard "T" seal.
The trick when working with capillary tubing is to increase the size of the inner bore prior to sealing onto any other glass. This can be done by either heating the end of a tube or fire-cutting off a portion of the tube. The T tube of the T seal should be prepared just like a capillary butt seal.
For another view of working with capillary tubing, see how to do a butt seal.
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