I recently replaced the whole system on my T2. The two rear sections were simple enough, however the front section was a bit trickier.
You'll want to jack the car up as high you can and remove passenger side front wheel. This gives good access to two of the three studs at the manifold end. Then following some sound advice provided here I took the short propshaft off underneath the front exhaust section, and through the use of socket extensions and one of those universal joint type extensions you can get to the third nut at the manifold end comparitively easily. Having the propshaft removed also made threading the new pipe into place more simple.
Be careful with the nuts at the manifold end. One on mine was rusted tight and I broke the stud. If you have time I would recommend a few liberal applications of WD40, or similar before the job. Also use good fitting sockets ( sorry I can't remember the size).
You'll need it jacked up high to get under the car easy, but I'm quite a fatty!
Good luck with it.
Alan