Can anyone tell me how to reach rear plugs in venture 98 for tune up?

its hard to me to make a tune up to my van 98 venture but i am tring to do it with myself just need a little help?
Can anyone tell me how to reach rear plugs in venture 98 for tune up?
Remove the "doghouse" cover inside the van. Or get at the plug from underneath the van. But the cover is the best way to go

lily