Calum Davenport's early header, a Christopher Samba own goal plus stoppage-time strikes by Craig Bellamy and Carlton Cole made this look like a right Hammering but, in truth, the scoreline flattered the club he joined as a schoolboy in the early-eighties.
Indeed, Jason Roberts' first-half strike had ensured that Blackburn were still in it at the break and the Rovers striker was also denied an equaliser, when Robert Green saved his 47th-minute penalty.
Add in injured Roque Santa Cruz's half-hour departure and replacement Matt Derbyshire's dubiously disallowed goal and it all made for a miserable afternoon for Ince, who had arrived at Upton Park in third place, thanks to an opening-day win at Everton and last week's draw with Hull City.
Both sides had enjoyed carbon-copy 4-1 Carling Cup victories in midweek and made wholesale changes to their starting line-ups, too.
Paul Robinson, Andre Ooijer, Stephen Warnock, Roberts, Santa Cruz, Samba, Steven Reid and Vince Grella were the eight players recalled by Ince following Wednesday's win against Grimsby Town.
And after finally seeing off Macclesfield Town in extra-time, Alan Curbishley made five changes of his own as Lucas Neill, Mark Noble, Scott Parker, Matthew Etherington and Cole each returned to the Hammers' starting line-up.
While Ince had been back to Upton Park several times as a player since his acrimonious departure in 1989, this was the first time he had sat in the dug-out as a manager.
Sure enough, within seconds of the kick-off, his first strut into the technical area was met by a predictable chorus of boos from an East End crowd, who have never forgiven him for being photographed in a Manchester United shirt, while still a Hammer.
On 12 minutes, however, those snarls dramatically changed to smiles, when Davenport soared above Ryan Nelsen to meet Julien Faubert's inswinging corner and claim his first-ever goal for West Ham United with a crashing, six-yard header.
With 20 minutes on referee Mike Riley's watch, the Hammers doubled their lead. Once again, Frenchman Faubert was the architect, inviting Noble to sweep a 15-yarder goalwards and, under pressure from Dean Ashton on the six-yard line, the red-faced Samba's attempted haymaker skewed beyond the flat-footed Robinson.
But Rovers replied within seconds, when Grella nodded a poor defensive clearance to Roberts, who spun Davenport and advanced into the West Ham area, where he threaded a close-range shot past the woefully exposed Robert Green to collect a second, successive Premier League goal.
By now, though, Santa Cruz was crocked and, as the half-hour mark approached, he was replaced by Matt Derbyshire, who forced the ball over the line with his first touch, only to see his effort ruled out by a debatable offside flag.
Although Morten Gamst Pedersen sent a 25-yard free-kick just a whisker wide, it had certainly been a better opening half for Curbishley than the frustrated Ince, who had also seen Grella, Ooijer and Roberts cautioned.
New-signing Keith Andrews replaced Grella at the interval and, within seconds of the restart, Roberts spurned a great chance to level, when his low spot-kick towards the bottom right-hand corner was saved by Green, after Cole had handled Pedersen's free-kick.
On the hour, Davenport sent an electrifying, angled volley beyond the far post and, seconds later, Derbyshire danced into the West Ham area and deposited the ball onto the roof of Green's net.
With 20 minutes remaining, Brett Emerton's downward header bounced off the well-placed Green's shin and then the Hammers keeper did well to hold Reid's 25-yard sizzler.
At other end, Robinson was equally defiant, beating away substitute Bellamy's scorching snapshot, before clawing Cole's curler around his left-hand post, but in stoppage time, the Rovers keeper twice found himself picking the ball out of the net.
First the escaping Bellamy raced onto Neill's lofted free-kick forward and lashed an angled ten-yard shot under the far angle and, with Rovers now in total disarray, Valon Behrami's cutback was unselfishly squared across goal by Parker and Cole simply made it Rover and out for the incensed Ince.