"I don't see how in conscience the LDs could accept...."

Unfortunately these inducements (or bribes) are aimed at the leadership and not the rank and file party members or, indeed, the people who voted for them believing they were a viable alternative to the tories

The argument goes that because of the number of seats the Lib-Dems would not have to enter into a full coilition with the Tories as they would have to with the Labour Party.
As such they would only need to abstain to allow legislation to pass and could claim subsequently, but maybe not in all sincerity, that they didn't vote for it.

I'm inclined to agree with Richard that the effect on the parlimentary and national party of such an alliance would ultimately be more harmful than any short term gain of a place in government.