The best scenario for Dallas is for Portland to release Wallace... which would allow the Mavs to sign him for the exception.
Problem is Wallace still has too much value so Portland is demanding (1) talent with a good contract or (2) expiring contracts + draft pick(s)
Dallas does not have expiring contracts so if they want 'Sheed the Mavs will likely have to involve a third team. With the hiring of Isiah Thomas in NYC look for something along the lines of Jamison to Knicks; McDyess to Portland; Wallace to Dallas. (Others will need to be included as cap filler...)
Other players to watch that could help Dallas land Wallace:
> Ilgauskas
> Ratliff
> Kukoc
> Gugliotta
LINK TO FURTHER DISCUSSION