Time-resolved infrared-ultraviolet double resonance (IR-UV DR) spectroscopy provides a distinctive way to examine collision-induced state-to-state energy transfer between rotational J-levels in vibrational manifolds of small polyatomic molecules, such as acetylene (C2H2) in its electronic ground state R. We consider the 4v(CH) rovibrational manifold of C2H2 at similar to 12 700 cm(-1), where, the principal source of IR-brightness is the (v(1) + 3v(3)) or (1 0 3 0 0)degrees Sigma(+)(u) vibrational combination level. In this highly congested manifold, anharmonic, l-resonance, and Coriolis couplings affect the J-levels of interest, implicating them in a complicated variety of intramolecular dynamics. Previous papers of this series have reported several seemingly anomalous J-resolved phenomena induced by collisions in C2H2 gas at room temperature with pressures and IR-UV pump-probe delay intervals corresponding to remarkably high Lennard-Jones collisional efficiencies P, odd-Delta J rotational energy transfer (10(-3) < P < 0. 1), in addition to regular even-Delta J transfer (P approximate to 0.3 for typical vertical bar Delta J vertical bar = 2 transfer); particular rovibrational "gateway" channels, such as via (v(1) + 3v(3)) Sigma(+)(u) J = 12 (with P as high as similar to 0. 1); an apparently ubiquitous collision-induced quasi-continuous background (10-3 < P < 0. 1) that accounts for much of the observed collision-induced odd-Delta J satellite structure. These phenomena have been characterized by means of systematic IR-UV DR kinetic measurements, with IR pump and UV probe wavelengths and sample pressure fixed while the IR-UV pump-probe delay is scanned. In this paper, a detailed master-equation model is constructed to provide a satisfactory phenomenological fit to the IR-UV DR kinetic data, thereby offering mechanistic insight. This model includes collision-induced energy transfer between discrete rovibrational levels in an IR-bright manifold V and a quasi-continuous bath B, mediated by a J-specific gateway manifold G.