Moving text columns, when it actually is large

I have to restructure some tables, coalescing common elements from three
tables (sub-classes) into a single table (super-class). Each source
table has a text field which actually gets stuffed with a largish (1Mb+)
blob of xml.

Is there any way to simply, um, er, transplant the pointer rather than
actually copy the data?

Ever hopeful,
rjs