  We propose a projected shell model (PSM) for description of stellar
weak-interaction rates between even-even and odd-odd nuclei with extended
configuration space where up to six-quasiparticle (qp) configurations are
included, and the stellar weak-interaction rates for eight $rp$-process
waiting-point (WP) nuclei, $^{64}$Ge, $^{68}$Se, $^{72}$Kr, $^{76}$Sr,
$^{80}$Zr, $^{84}$Mo, $^{88}$Ru and $^{92}$Pd, are calculated and analyzed for
the first time within the model. Higher-order qp configurations are found to
affect the underlying Gamow-Teller strength distributions and the corresponding
stellar weak-interaction rates. Under $rp$-process environments with high
temperatures and densities, on one hand, thermal population of excited states
of parent nuclei tends to decrease the stellar $\beta^+$ decay rates. On the
other hand, the possibility of electron capture (EC) tends to provide
increasing contribution to the rates with temperature and density. The
effective half-lives of WP nuclei under the $rp$-process peak condition are
predicted to be reduced as compared with the terrestrial case, especially for
$^{64}$Ge and $^{68}$Se.
