I practice recording for convolution by simply clapping in the hand on the particular location. Later on the computer I cut away the inital sound of the clap to have only the tail of reverbration available. May be not that accurate in the scientific way but works well for me.

But convolution can do more than adding room to recordings, I got incredible results by convolving synthetic sounds (which have to have a lot of harmonics to be useful, simular as in vocoding which is close to convolution) with speech as 'impulse'.

Cheers,

Malte