Getting the "Qua" out of the "Quack" sound from the wah is going to be difficult with EQ. You'll need Parametric EQ for it, two preferably. Even then it's going to alter the sound the moment you move the wah pedal again from it's toe position. The best & easiest would be to have a switchless wah to do a quick ON/OFF. Besides that there is the option of Auto-Wah or Touch-Wah, the G3 probably has one. Give that a try. Maybe create two patches with same settings & then switch between them whenever the part comes up, one with the Auto in Stomp 1 spot & the other with something else you were using.
Unrelated to this, did you get the new laney A50(?)amp yet?
PRS SE[Soapbar,Semi Hollow], Fender Squier CV Strat, ESP LTD Viper 400, Laney[LH20 head, LC50Mk.II, LX65R], GS412IS(WGS ET65 loaded), Boss TU3, Dunlop ZW45 Wah, Boss GT10, Shure SM57, Sennheiser E614, L6 Pod Studio UX2, Abelton Live 8, Reaper, Seymour Duncan[SP90-1,SP90-2,SH10 bridge,SH4,SH PG1,SH55], DiMarzio[DP100,DP159,DP103]